Category: Programming

ReactNative – iOS Xcode 14 + MacOS X Ventura – build errors Duplicate Symbols for Architecture arm64

Building ReactNative Apps is always little hard when there is an Operating System Update along with that Xcode updated. Every time when Xcode is updated to a newer version, Apple make some changes which will start affecting iOS app build in ReactNative.

ReactNative iOS App build errors with Xcode 14 and Mac OS X Ventura

Recently when I updated Mac OS X Ventura, It also forced me to update Xcode to latest version 14. After Xcode update, my ReactNative App started failing with lots of errors. I have ReactNative app which is using RN version v0.59.9, Xcode started throwing linking errors like

42 Duplicate symbols for architecture arm64

the complete error looks as follows

duplicate symbol '_OBJC_CLASS_$_FBSDKBase64' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKBase64.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKBase64.o)
duplicate symbol '_OBJC_METACLASS_$_FBSDKBase64' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKBase64.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKBase64.o)
duplicate symbol '_OBJC_CLASS_$_FBSDKBasicUtility' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKBasicUtility.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKBasicUtility.o)
duplicate symbol '_OBJC_METACLASS_$_FBSDKBasicUtility' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKBasicUtility.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKBasicUtility.o)
duplicate symbol '_OBJC_CLASS_$_FBSDKCrashHandler' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKCrashHandler.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKCrashHandler.o)
duplicate symbol '_OBJC_METACLASS_$_FBSDKCrashHandler' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKCrashHandler.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKCrashHandler.o)
duplicate symbol '_OBJC_CLASS_$_FBSDKLibAnalyzer' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKLibAnalyzer.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKLibAnalyzer.o)
duplicate symbol '_OBJC_METACLASS_$_FBSDKLibAnalyzer' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKLibAnalyzer.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKLibAnalyzer.o)
duplicate symbol '_OBJC_CLASS_$_FBSDKTypeUtility' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKTypeUtility.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKTypeUtility.o)
duplicate symbol '_OBJC_METACLASS_$_FBSDKTypeUtility' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKTypeUtility.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKTypeUtility.o)
duplicate symbol '_OBJC_IVAR_$_FBSDKURLSession._session' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKURLSession.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKURLSession.o)
duplicate symbol '_OBJC_CLASS_$_FBSDKURLSession' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKURLSession.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKURLSession.o)
duplicate symbol '_OBJC_METACLASS_$_FBSDKURLSession' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKURLSession.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKURLSession.o)
duplicate symbol '_OBJC_IVAR_$_FBSDKURLSession._delegateQueue' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKURLSession.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKURLSession.o)
duplicate symbol '_OBJC_IVAR_$_FBSDKURLSession._delegate' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKURLSession.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKURLSession.o)
duplicate symbol '_OBJC_IVAR_$_FBSDKURLSessionTask._handler' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKURLSessionTask.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKURLSessionTask.o)
duplicate symbol '_OBJC_IVAR_$_FBSDKURLSessionTask._loggerSerialNumber' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKURLSessionTask.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKURLSessionTask.o)
duplicate symbol '_OBJC_IVAR_$_FBSDKURLSessionTask._task' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKURLSessionTask.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKURLSessionTask.o)
duplicate symbol '_OBJC_CLASS_$_FBSDKURLSessionTask' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKURLSessionTask.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKURLSessionTask.o)
duplicate symbol '_OBJC_METACLASS_$_FBSDKURLSessionTask' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKURLSessionTask.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKURLSessionTask.o)
duplicate symbol '_OBJC_IVAR_$_FBSDKURLSessionTask._requestStartDate' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKURLSessionTask.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKURLSessionTask.o)
duplicate symbol '_OBJC_IVAR_$_FBSDKURLSessionTask._requestStartTime' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKURLSessionTask.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKURLSessionTask.o)
duplicate symbol '_FBSDKAppEventCity' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKAppEvents.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKUserDataStore.o)
duplicate symbol '_FBSDKAppEventCountry' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKAppEvents.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKUserDataStore.o)
duplicate symbol '_FBSDKAppEventGender' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKAppEvents.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKUserDataStore.o)
duplicate symbol '_FBSDKAppEventZip' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKAppEvents.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKUserDataStore.o)
duplicate symbol '_FBSDKAppEventEmail' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKAppEvents.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKUserDataStore.o)
duplicate symbol '_FBSDKAppEventDateOfBirth' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKAppEvents.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKUserDataStore.o)
duplicate symbol '_FBSDKAppEventState' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKAppEvents.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKUserDataStore.o)
duplicate symbol '_OBJC_CLASS_$_FBSDKUserDataStore' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKUserDataStore.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKUserDataStore.o)
duplicate symbol '_OBJC_METACLASS_$_FBSDKUserDataStore' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKUserDataStore.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKUserDataStore.o)
duplicate symbol '_FBSDKAppEventPhone' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKAppEvents.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKUserDataStore.o)
duplicate symbol '_FBSDKAppEventFirstName' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKAppEvents.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKUserDataStore.o)
duplicate symbol '_FBSDKAppEventLastName' in:
    /Users/xyz/Library/Developer/Xcode/DerivedData/MyProject-bmkdjxadfihkgxdpmjllovjakstn/Build/Products/Release-iphoneos/FBSDKCoreKit/libFBSDKCoreKit.a(FBSDKAppEvents.o)
    /Users/xyz/MyComputer/Development/MyProject/SourceCode/MyBranches/saz_mobile/mobile_rn_dev/sazappmobile/MyProject/ios/Pods/FacebookSDK/FBSDKCoreKit_Basics.framework/FBSDKCoreKit_Basics(FBSDKUserDataStore.o)
ld: 42 duplicate symbols for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

When I started looking for solution, I found multiple solutions, which actually worked for many people, however for me none of those solutions worked.

Solution for Duplicate Symbols for architecture arm64 – which worked for me

Steps to resolve

  1. Open your project in Xcode
  2. Click on Pods project from your project navigator as shown in below diagram
    then select Build Phases and select the project target in which you are getting errors. For me all linking errors were for FBSDKCore, you can find that by seeing the error.

  4. Then from error get the file name for which you are getting duplicate symbol. for example if error has
    duplicate symbol ‘_FBSDKAppEventLastName’ in: /libFBSDKCoreKit.a(FBSDKAppEvents.o)
    Then find file FBSDKAppEvents.m from the search box given in above screenshot.
  5. Find the file and select the file and delete by clicking on delete(-) icon in the Xcode. ( refer below screenshot)
  6. Since in my case there are 42 linking errors, all the errors are coming from more than 4 to 5 different files. I deleted all the files one by one.
  7. This resolved all 42 linking error.

Basically the error appears when same implementation is referenced more than one in the project. Which mean in my case some of the .m files from FBSDKCoreKit are added more than once, it is difficult to find how those files added twice, but usually it happens when libraries are linked through pods as well as manually ( typically in old projects libraries might have also linked using ReactNative link command)

Now question is why Xcode 14 started giving errors? which was not the case earlier with lower version of Xcodes ? this is basically because the latest Xcode checks strictly many things and it starts complaining.

Is it the only solution which fix this issue ? well that I am not sure, there are many more solutions giving in StackOverflow as well as GitHub, some fixes might work for you. Here are those references for you, in case my fix doesn’t work for you 🙂

References:

1. Github Post- duplicate symbols for architecture x86_64 React Ntaive version 0.64 #32016

2. Github Post – duplicate symbols for architecture x86_64 React Ntaive

3. Stack over flow post – Duplicate Symbols for Architecture arm64

Advantages of React Stateless Functional Components

Advantages of React Stateless Functional Components

Before reading this post, if you have not gone through what are functional components in Reactjs then kindly go through this post

In this post we will see what are the advantages of functional posts in React js. If you check your react js code, you will quickly figure out that many components do not actually need state, they do get data from parent as props and will render the information. In such a case why to introduce state and make it complicated? rather I would prefer calling a function which returns me a component. Isn’t it so simple ? React 14 introduced Functional Components, also called as stateless components and removed unnecessary complications. So let us explore what are the advantages of stateless components 

Advantages of React Functional/Stateless Components: Ref

1. More focused on presentation

React is forcing us to write components which are used only for presentational purpose, these components are useful for dumb presentational purpose only, that focus on UI rather than behaviour. Technically speaking its normal tendency to go for stateful components, doing that way we are making our code easily hackable where every damn component keeps its own local state. Functional components allowing us to have pure components which just focus on presentation. where as the state is maintained by few higher level components.

2. Gain in Performance

Stateless components will bring performance gain since there is no state and lifecycle of a component. React doesn’t need to have unnecessary check and memory allocations which eventually brings performance boost.

3. Clean and Optimised Code

Stateless components reduce lot of code, almost 20% – 30% reduction in code and hence the code will become clean and optimised.

4. Easy to debug

Functional components are pure components and helps your to analyse your code quickly and you no need to put log if assert calls everywhere to debug. 

React more on React

React More on ReactNative 

React Native List View : Animate Rows While Scrolling Using FlatList

React Native List View : Animate Rows While Scrolling Using FlatList

In my previous post I have written about how to use React Native FlatList and we have seen the issues we face with pagination also how to add a loading indicator in the footer of FlatList. You can first read about it Link In this post we will see how to animate the rows while scrolling a FlatList.

Animating Rows In React Native FlatList :

To achieve animation for FlatList Rows, you have to install an npm module react-native-animatable, which provides variety of smooth animations for List Rows.

Installation of npm module:

$ npm install react-native-animatable --save

 

To make a continuous animation do this

<Animatable.Text animation="slideInDown" iterationCount={5} direction="alternate">Up and down you go</Animatable.Text>
<Animatable.Text animation="pulse" easing="ease-out" iterationCount="infinite" style={{ textAlign: 'center' }}>❤</Animatable.Text>

 

To animate rows in FlatList Rows do this

import * as Animatable from 'react-native-animatable';

class FlatListRow extends Component {
  render(){
    return(
      <Animatable.View animation='fadeInUp'>;
       <TouchableWithoutFeedback>;
          // here your row component
       </TouchableWithoutFeedback>;
      </Animatable.View>;
    );
  }
}


Variety of animations are supported in this React Native Animation library











ReactJS: Google Map Component
 




ReactJS: Google Map Component


Steps to implement google maps in Facebook’s ReactJS Web Application


1. Add npm module in your project for react-google-maps


npm install --save react-google-maps # or
yarn add react-google-maps


 


Reference : https://github.com/tomchentw/react-google-maps


Before this you have to include google maps api sdk in your index.ejs file 


 <script src=”https://maps.googleapis.com/maps/api/js?v=3.27&libraries=places,geometry&key=<YOUR_API_KEY>”></script>


How to get Google Maps Api Key ? 


Follow the steps given in this link


2. Create Google Map Handler Component


















'use strict';

import React from 'react';
import { connect } from 'react-redux';
import { bindActionCreators } from 'redux';
import update from 'react-addons-update';

import canUseDOM from 'can-use-dom';

import raf from 'raf';
import GoogleMapComponent from './gMapComponent';

const geolocation = (
  canUseDOM && navigator.geolocation ?
  navigator.geolocation :
  ({
    getCurrentPosition(success, failure) {
      failure('Your browser doesnt support geolocation.');
    },
  })
);

class GoogleMapHandlerComponent extends React.Component {

    state = {
      bounds: null,
      center: null,
      content: null,
      radius: 400,
      markers: []
    };

  constructor(props) {
    super(props);
    if (props !== null &&
        props !== undefined &&
        props.location !== null &&
        props.location !== undefined &&
        props.location.markers !== null &&
        props.location.markers !== undefined) {
      const locationInfo = {
        center: props.location.center,
        markers: props.location.markers
      };
      this.state = locationInfo;
    }
  }

  componentDidMount() {
    const tick = () => {
      if (this.isUnmounted) {
        return;
      }
      this.setState({ radius: Math.max(this.state.radius - 5, 0) });
      if (this.state.radius > 10) {
        raf(tick);
      }
    };
    geolocation.getCurrentPosition((position) => {
      if (this.isUnmounted) {
        return;
      }
      this.setState({
        center: {
          lat: position.coords.latitude,
          lng: position.coords.longitude,
        },
        content: 'Location found using HTML5.',
      });

      raf(tick);
    }, (reason) => {
      if (this.isUnmounted) {
        return;
      }
      this.setState({
        center: {
          lat: 60,
          lng: 105,
        },
        content: 'Error: The Geolocation service failed (${reason}).',
      });
    });

    if (document.getElementsByClassName('pac-container').length > 0) {
      const gmapSearchResultsBox = document.getElementsByClassName('pac-container')[0];
      gmapSearchResultsBox.style.zIndex = '2000';
    }
  }

  componentWillReceiveProps(nextProps) {
    if (nextProps !== null &&
        nextProps !== undefined &&
        nextProps.location !== null &&
        nextProps.location !== undefined &&
        nextProps.location.markers !== null &&
        nextProps.location.markers !== undefined) {
      this.setState({
        center: nextProps.location.center,
        markers: nextProps.location.markers
      });
    }
  }

  componentDidUpdate() {
    if (document.getElementsByClassName('pac-container').length > 0) {
      const gmapSearchResultsBox = document.getElementsByClassName('pac-container')[0];
      gmapSearchResultsBox.style.zIndex = '2000';
    }
  }
  componentWillUnmount() {
    this.isUnmounted = true;
  }

  isUnmounted = false;

 handleMapMounted = this.handleMapMounted.bind(this);
 handleBoundsChanged = this.handleBoundsChanged.bind(this);
 handleSearchBoxMounted = this.handleSearchBoxMounted.bind(this);
 handlePlacesChanged = this.handlePlacesChanged.bind(this);
 handleMarkerClose = this.handleMarkerClose.bind(this);
 handleMarkerClick = this.handleMarkerClick.bind(this);

 handleMapMounted(map) {
     this._map = map;
   }

   handleBoundsChanged() {
     this.setState({
       bounds: this._map.getBounds(),
       center: this._map.getCenter(),
     });
   }

   handleSearchBoxMounted(searchBox) {
     this._searchBox = searchBox;
   }
   handleLoadPlaces(markers) {

   }
   handlePlacesChanged() {
     const places = this._searchBox.getPlaces();

     // Add a marker for each place returned from search bar
     const markers = places.map(place => ({
       position: place.geometry.location,
     }));

     // Set markers; set map center to first search result
     const mapCenter = markers.length > 0 ? markers[0].position : this.state.center;
     this.setState({
       center: mapCenter,
       markers,
     });
     this.props.handleLocationChange(mapCenter, places);
   }

   // Toggle to 'true' to show InfoWindow and re-renders component
  handleMarkerClick(targetMarker) {
    this.setState({
      markers: this.state.markers.map(marker => {
        if (marker === targetMarker) {
          if (marker.showInfo) {
            return {
              ...marker,
              showInfo: false,
            };
          }
          return {
            ...marker,
            showInfo: true,
          };
        }
        return marker;
      }),
    });
  }

  handleMarkerClose(targetMarker) {
    this.setState({
      markers: this.state.markers.map(marker => {
        if (marker === targetMarker) {
          return {
            ...marker,
            showInfo: false,
          };
        }
        return marker;
      }),
    });
  }

  render() {
    return (
      <GoogleMapComponent
        containerElement={
          <div style={{ height: '100%' }} />
        }
        mapElement={
          <div style={{ height: '100%' }} />
        }
        center={this.state.center}
        onMapMounted={this.handleMapMounted}
        onBoundsChanged={this.handleBoundsChanged}
        onSearchBoxMounted={this.handleSearchBoxMounted}
        bounds={this.state.bounds}
        onPlacesChanged={this.handlePlacesChanged}
        onMarkerClick={this.handleMarkerClick}
        onMarkerClose={this.handleMarkerClose}
        markers={this.state.markers}
      />
    );
  }
}

 function mapDispatchToProps(dispatch) {
   return bindActionCreators({ }, dispatch);
 }

export default connect(null, mapDispatchToProps)(GoogleMapHandlerComponent);



 


3. Create Google Map Component, this component uses the components of react-google-maps module


















'use strict';

import React from 'react';
import IconButton from 'material-ui/IconButton';

import {
  withGoogleMap,
  GoogleMap,
  Circle,
  InfoWindow,
  Marker
} from 'react-google-maps';

import SearchBox from 'react-google-maps/lib/places/SearchBox';
import GoogleMapMarkerInfoWindow from './gMapMarkerInfoWindow';

import layoutStyle from '../../../constants/layoutStyle';

const INPUT_STYLE = {
  boxSizing: 'border-box',
  MozBoxSizing: 'border-box',
  border: '1px solid transparent',
  width: '240px',
  height: '32px',
  marginTop: '27px',
  marginRight: '20px',
  padding: '0 12px',
  borderRadius: '1px',
  boxShadow: '0 2px 6px rgba(0, 0, 0, 0.3)',
  fontSize: '14px',
  outline: 'none',
  textOverflow: 'ellipses',
};

const GoogleMapComponent = withGoogleMap(props => (
  <GoogleMap
    ref={props.onMapMounted}
    defaultZoom={15}
    center={props.center}
    onBoundsChanged={props.onBoundsChanged}
  >
    <SearchBox
      ref={props.onSearchBoxMounted}
      bounds={props.bounds}
      controlPosition={google.maps.ControlPosition.TOP_RIGHT}
      onPlacesChanged={props.onPlacesChanged}
      inputPlaceholder='Search Location'
      inputStyle={INPUT_STYLE}
    />

    {props.markers.map((marker, index) => (
      <Marker
        key={index}
        position={marker.position}
        onClick={() => props.onMarkerClick(marker)}
      >
        {/*
           Show info window only if the 'showInfo' key of the marker is true.
           That is, when the Marker pin has been clicked and 'onCloseClick' has been
           Successfully fired.
        */}
        {marker.showInfo && (marker.pinOnly === null ||
        marker.pinOnly === undefined || !marker.pinOnly) && (
          <InfoWindow onCloseClick={() => props.onMarkerClose(marker)}>
            <GoogleMapMarkerInfoWindow infoContent={marker.infoContent} />
          </InfoWindow>
        )}
      </Marker>
    ))}

    {props.center && (
      <Circle
        center={props.center}
        radius={props.radius}
        options={{
          fillColor: 'red',
          fillOpacity: 0.20,
          strokeColor: 'red',
          strokeOpacity: 1,
          strokeWeight: 1,
        }}
      />
    )}
  </GoogleMap>
));

export default GoogleMapComponent;





4. Use Google Map Handler component whereever you wish to place the map




render() {
      const handleLocationChange = this.handleLocationChange;
      const mapsComponent = (
        <GoogleMapHandlerComponent
          location={this.props.location}
          handleLocationChange={handleLocationChange.bind(this)}
        />);
      return (
        <div
          id='mapId'
          style={{ width: '450px', height: '350px' }}
        >
          {mapsComponent}
        </div>
      );
    }




Note you have to pass your current location to land user on his current location, else any other location which is default location.

 and a callback for handling change in location.


ReactJS google map location change callback will be called by react-google-maps library when there is change in location,

 like user searched some location


Also check stateless react components : http://knowledge-cess.com/reactjs-functional-or-stateless-components/


 











Regular Expressions : How Exactly they work internally ?
 




Regular Expressions : How Exactly they work internally ?


Regular expressions were playing major role in computers from several decades, they are not as simple as we think. They are need extensive computational power, a decade before regular expressions were a big headache for computer programmers and scientists because they were consuming lot of time to complete the task.










History behind Regular Expressions :


A neuroscientist  who tried to understand how the human brain could produce complex patterns using simple cells that are bound together. In 1943, Warren McCulloch and Walter Pitts published “A logical calculus of the ideas immanent in nervous activity”.  this paper had a great influence on computer science during that time. In 1956, mathematician Stephen Kleene developed this model one step further. In the paper “Representation of events in nerve nets and finite automata” he presents a simple algebra. The terms Regular Sets and Regular Expressions were born from then. As mentioned above, Kleene’s algebra had only two operations and one function. In 1968, the Unix pioneer Ken Thompson published the article “Regular Expression Search Algorithm” in Communications.


A Pattern in regular expression :


How to learn regular expressions ? How to understand regular expressions?. They look confusing to understand regular expression but regular expressions are an elegant way to do some string manipulations.


We have studied finite automata and the regular expressions all just works on this theory, but Most modern programming languages (Perl, Python, Ruby, Java (and JVM based languages), C#) do not use this approach rather they use recursive backtracking approach. But finite automata is really good to understand regular expressions with its state diagrams and not a bad idea to implement in this approach may be recursive backtracking is better. So do you need a help to understand regular expression? here it is…


Let us take one example, Validating an email address










If this is your regular expression


[a-z][a-z|0-9|]*([_][a-z|0-9]+)*([.][a-z|0-9]+([_][a-z|0-9]+)*)



The respective state diagram might look like below


Regular expression state diagram
Regular expression state diagram


Regular expression parser Source Code


If you want to try out with your own regular expression code you can better go through here 


Tool to visualise your regular expression : https://www.debuggex.com/


http://www.codeproject.com/Articles/5412/Writing-own-regular-expression-parser











MIT’s Robot can jump over hurdles : Cheetah robot
 




MIT’s Robot can jump over hurdles : Cheetah robot


Human’s can achieve anything, human mind is the greatest gift of god. If you run in hurry or if you run on a moving floor your mind will get confused and some times you fell down. If you are not practiced then you can’t even cross two three hurdles continuously, you will fell down. Have you ever wondered a robot can do this ? it is so difficult to program even a simplest automation or even a simplest robot which can just move by itself. Now we have everything ready made so you may say it is not so difficult, but Cheetha which can run and jump over the hurdles ? really challenging.


A MIT’s Cheetah Robotic TEAM


Deborah Ajilo, Negin Abdolrahim Poorheravi,John Patrick Mayo,Justin Cheung, Sangbae Kim, Shinsuk Park, Kathryn L. Evans, and Matt Angle.  Will Bosworth, Joao Luiz Almeida Souza Ramos, Sehyuk Yim, Albert Wang, Meng Yee Chuah, and Hae Won Park.


Algorithm Behind MIT’s Cheetha robot :


The bounding algorithm which made this possible will program each of the robot’s legs to exert a certain amount of force in the split second during which it hits the ground, in order to maintain a given speed: In general, the faster the desired speed, the more force must be applied to propel the robot forward.


the cheetaha robot adopts the force as per the surface and hence it successfully passed the test in grassy area and treadmill.Robot can run 16 km/h, jump about 40 centimetres high, land safely and continue running for at least 15 minutes .


Technical Details of MIT’s Bounding Algorithm and Robotic Cheetah


It took more than 5 years to achieve this and Cheetah 2 contains the custom electric motor designed by Jeffrey Lang, the Vitesse Professor of Electrical Engineering at MIT and the amplifier designed by David Otten, a principal research engineer in MIT’s Research Laboratory of Electronics. 


“bounding algorithm” calculates the varying amounts of force required to propel an animal forward or to jump over obstacles. Algorithm models the running mechanics of world-class sprinters like Olympian Usain Bolt: the faster the desired speed, the greater the force the legs exert.


This robotic cheetah carries out its movements with the help of battery powered electric motors which do not make much noise even.  Though the US-military has been trying for several years to make a stealthy and fast robot, it hadn’t been successful until now so this DARPA funded research by the MIT researchers may just open a whole new vision regarding the making of a stealthier bot.


 













Android: ItemClickListner with CheckBox or RadioButton.
 




Android: ItemClickListner with CheckBox or RadioButton.


Lets take a scenario to understand the need of a listview which will have checkbox embedded in it.


Consider the flipkart mobile app, in that we want to compare 2 or more products, in order to do that I will go on selecting the items which I want to compare and then click on the compare button.


 


So we have multiple items in that and hence we cant use the android built in types for creating the list view. Hence we need to follow the below mentioned approach.


 


    

  1. Create an activity, which contains 2 listviews, one listview for displaying all available mobiles and another listview for displaying selected mobiles.
    2. 

  2. Create an adapter for filling the mobile list for the above mentioned listviews.
    3. 

  3. The layout which will be used for creating row which will make ItemClickListner work is as follows,
    4. 



 





    

    
    
        
    

    
        
        
        





Observe the following attributes for Checkbox,


        android:focusable="false"
        android:focusableInTouchMode="false"
        android:clickable="false"




These make the checkbox non clickable and eventually the event will be transferred to its parent i.e the row and hence the ItemClickListner will be invoked.


You can download the files here











How To Make You Web Site Faster : HTML , Javascript Tricks
 




How To Make You Web Site Faster : HTML , Javascript Tricks


 


The performance of your web application is highly important factor to get more user visits, experts have given many advices to improve the performance of a web application and few are listed below.


1. Meta refresh – Meta refresh is a method of instructing a web browser to automatically refresh the current web page or frame after a given time interval, using an HTML meta element with the http-equiv parameter set to “refresh” and a content parameter giving the time interval in seconds.


Avoid Meta refresh as much as possible. This will slow down your site.










2. @imports will synchronously load the style sheet, Avoiding @import will improve the performance of your site. Instead of @imports use LINK tag as follows


Use

 <link rel=’stylesheet’ href=’knowledge-cess-style.css’>


Than   <style> @import url(‘knowledge-cess-style.css’); </style>


3. Avoid use of multiple framework – Some people use JQuery for some functionality and DOJO for some functionality . Loading of framework will take time and your app becomes heavy. Stick to one framework.


4. Placing scripts at the end


Most people will load all their scripts at the beginning of the page. Load scripts at the end, some times it is not possible, it gives an error if a function being used in the page. In that case make two js files and keep necessary stuff in one js and load it at the beginning.










5. Use ‘differ’ attribute to if some scripts must be loaded at the beginning.


<script src=“knowledge-cess.js” defer></script>


6. To construct dynamic pages it is better to use .innerHTML rather than always creating DOM elements dynamically.


7. Referencing more DOM elements using document.querySelectorAll()


var matches = document.querySelectorAll("div.note, div.alert"); Reference 


8. Use Javascript timers carefully. Don't let timers run unnecessarily.

9. Javascript animation and Math


 Time to play with Math now, animation is nothing but playing with frames, higher the frame rate smoother the animation and more frames means more processing. The time interval we set for an animation should depend on screen refresh rate.


Understand how Javascript Animation related to Screen refresh rate 


Most screens have refresh rate of 60Hz, so 60 frames per second (60fps) is best frame rate.

 Javascript timer will be set in milliseconds. so considering 1000ms and 60FPS which will give

 1000ms/60fps = 16.7ms. so it is best timer value, so set 16.7ms or 17ms for your javascript timer while playing with animations.


function setInterval(function(){
          animate();
 },17);


10. Performance factor for PNG and JPG – PNG will be of more size compared to jpg but jpg uses more complicated decoding algorithm compared to png.


Image format PnG vs JPG and performance

 The reason png size will be more is because png format will use lossless compression algorithm and jpg will use lossy compression algorithm.

11. Using requestAnimationFrame : Mozilla team proposed requestAnimationFrame method to over come from performance issues in javascript animations. Have a look into this Link

There Many more performance tuning techniques.Now let us look into some best practices of javascript


 


Best Practices in Javascript


 1. Use Shortcut notations


var cities = ["Bangalore","Delhi","Mysore"]


than


var cities = new Array();
     cities[0]='Bangalore'; 
     cities[1]='Delhi';
     cities[2]='Mysore';


2. Keep related stuff together


Best Practice – 


var settings = function(){
     var userDefaults = {
         categories: {"defaultCategory" : "xyz", "lastCategory":"pqr"},
         modules : {}
        }

      function initUserDefaults(){ }


      function clearUserDefaults(){}
   } //End of settings


The above way is clean and better approach rather than separating all methods.


3. Do not use primitive types as objects


 var name = "Ram";  //Best practice
      var name = new String("Ram"); //Not recommended


4. Use === operator


   Always use === operator for comparison, It always converts (to matching types) before comparison.


   The === operator forces comparison of values and type:


 100 == "100" //true which causes problem most of the times
      100 === "100" //false Best Practice, strict type checking


5. Global Variables in Javascript


Global variables are not recommended, Avoiding global variables is best practice.


6. Using JSLint 


Identify most common problems in your javascript code using JSLint tool


 


Check : how Animation in javascript works and how CSS3 is better than jQuery – link