react-native-class-exists

Works currently with:

iOS	Android	Windows
Yes	No	No

Why would I use this?

The situation may arise where you want to incorporate 'new features' that may not run on all your users devices. For instance, a user with iOS 9 will not be able to use SiriKit, whereas a user with iOS 10 will. You can check at run time whether a class exists using this module. You can also use this module to check for device capabilities. For instance, being able to check if a user's device supports ARKit (even if they have iOS 11+, their hardware may not support it).

Getting started

$ npm install react-native-class-exists --save

Mostly automatic installation

$ react-native link react-native-class-exists

Manual installation

iOS

1. In XCode, in the project navigator, right click Libraries ➜ Add Files to [your project's name]
2. Go to node_modules ➜ react-native-class-exists and add RNClassExists.xcodeproj
3. In XCode, in the project navigator, select your project. Add libRNClassExists.a to your project's Build Phases ➜ Link Binary With Libraries
4. Run your project (Cmd+R)<

Android

1. Open up android/app/src/main/java/[...]/MainActivity.java

• Add import com.reactlibrary.RNClassExistsPackage; to the imports at the top of the file
• Add new RNClassExistsPackage() to the list returned by the getPackages() method

2. Append the following lines to android/settings.gradle:

   include ':react-native-class-exists'
   project(':react-native-class-exists').projectDir = new File(rootProject.projectDir, 	'../node_modules/react-native-class-exists/android')
   

3. Insert the following lines inside the dependencies block in android/app/build.gradle:

     compile project(':react-native-class-exists')
   

Static Functions:

function	arguments	notes
exists()	className, callback	If you just want to check if a certain class exists at runtime, this is how you do it.
classMethodResponse()	className, methodName, responseType, callback	Sometimes you want to be able to do more than just check if a class exists at runtime. Sometimes you need to call a class method and get a return value. This is how you do it. As of now, we only wrote the code to allow you to call static class methods with no arguments. Look below for a list of supported return types

Supported Return Types for classMethodResponse (ObjC types)	Javascript form returned
BOOL	Boolean
NSNumber	Number
NSString or String	String
Remember to include the correct returnType for the method you will be calling

Usage Examples

Checking if UIAlertController works (introduced in iOS 8)

import React, { Component } from 'react'
import { Platform } from 'react-native'
import ClassExists from 'react-native-class-exists'

export default class App extends React.Component {
    componentDidMount() {
      if (Platform.OS == 'ios') {
        ClassExists.exists("UIAlertController", exists=>{
            console.log(exists ? "It exists! " : "Does not exist")
        })
      }
    }
}

Checking if the user can make payments (checking for the class isn't enough. So we can check for the class, AND run a method if it exists, as well as get a return value)

if (Platform.OS == 'ios') {
  ClassExists.classMethodResponse("SKPaymentQueue", "canMakePayments", "BOOL", (success, response)=>{
    if (success && response) {
      console.log("User can make payments")
    } else {
      console.log("User cannot make payments")
    }
  })
}

Checking if the user's device will run ARKit (Augmented Reality Kit from iOS 11+)

if (Platform.OS == 'ios') {
  ClassExists.classMethodResponse("ARConfiguration", "isSupported", "BOOL", (success, response)=>{
    if (success) {
      if (response) {
        console.log("User can use ARKit")
      } else {
        console.log("User has software for ARKit, but device doesn't support it. (Probably iOS 11+, but not on a newer device)")
      }
    } else {
      console.log("User cannot use ARKit")
    }
  })
}