This section will be updated shortly showing an integration into a more real world application such as the 2048 app that was used for Objective-C and Swift.
React Native is great when you are starting a new mobile app from scratch. However, it also works well for adding a single view or user flow to existing native applications. With a few steps, you can add new React Native based features, screens, views, etc.
The keys to integrating React Native components into your iOS application are to:
Podfile
with subspec
s for all the React Native components you will need for your integration.RCTRootView
that points to your React Native component and its AppRegistry
name that you defined in index.ios.js
.react-native-xcode.sh
script).The keys to integrating React Native components into your Android application are to:
react-native
in your Android application root directory to create node_modules/
directory.com.facebook.react:react-native:+
and a maven
pointing to the react-native
binaries in node_nodules/
to your build.gradle
file.Activity
that creates a ReactRootView
.The Android Getting Started guide will install the appropriate prerequisites (e.g., npm
) for React Native on the Android target platform and your chosen development environment.
First, follow the Getting Started guide for your development environment and the iOS target platform to install the prerequisites for React Native.
CocoaPods is a package management tool for iOS and Mac development. We use it to add the actual React Native framework code locally into your current project.
It is technically possible not to use CocoaPods, but this requires manual library and linker additions that overly complicates this process.
Assume the app for integration is a 2048) game. Here is what the main menu of the native application looks like without React Native.
Assume the app for integration is a 2048 game. Here is what the main menu of the native application looks like without React Native.
React Native integration requires both the React and React Native node modules. The React Native Framework will provide the code to allow your application integration to happen.
package.json
#We will add the package dependencies to a package.json
file. Create this file in the root of your project if it does not exist.
Normally with React Native projects, you will put files like
package.json
,index.ios.js
, etc. in the root directory of your project and then have your iOS specific native code in a subdirectory likeios/
where your Xcode project is located (e.g.,.xcodeproj
).
Below is an example of what your package.json
file should minimally contain.
Version numbers will vary according to your needs. Normally the latest versions for both React and React Native will be sufficient.
Install the React and React Native modules via the Node package manager. The Node modules will be installed into a node_modules/
directory in the root of your project.
The React Native Framework was installed as Node module in your project above. We will now install a CocoaPods Podfile
with the components you want to use from the framework itself.
Before you integrate React Native into your application, you will want to decide what parts of the React Native Framework you would like to integrate. That is where subspec
s come in. When you create your Podfile
, you are going to specify React Native library dependencies that you will want installed so that your application can use those libraries. Each library will become a subspec
in the Podfile
.
The list of supported subspec
s are in node_modules/react-native/React.podspec
. They are generally named by functionality. For example, you will generally always want the Core
subspec
. That will get you the AppRegistry
, StyleSheet
, View
and other core React Native libraries. If you want to add the React Native Text
library (e.g., for <Text>
elements), then you will need the RCTText
subspec
. If you want the Image
library (e.g., for <Image>
elements), then you will need the RCTImage
subspec
.
After you have used Node to install the React and React Native frameworks into the node_modules
directory, and you have decided on what React Native elements you want to integrate, you are ready to create your Podfile
so you can install those components for use in your application.
The easiest way to create a Podfile
is by using the CocoaPods init
command in the native iOS code directory of your project:
The Podfile
will be created and saved in the iOS directory (e.g., ios/
) of your current project and will contain a boilerplate setup that you will tweak for your integration purposes. In the end, Podfile
should look something similar to this:
After you have created your Podfile
, you are ready to install the React Native pod.
Your should see output such as:
If you get a warning such as "The
swift-2048 [Debug]
target overrides theFRAMEWORK_SEARCH_PATHS
build setting defined inPods/Target Support Files/Pods-swift-2048/Pods-swift-2048.debug.xcconfig
. This can lead to problems with the CocoaPods installation", then make sure theFramework Search Paths
inBuild Settings
for bothDebug
andRelease
only contain$(inherited)
.
Now that we have a package foundation, we will actually modify the native application to integrate React Native into the application. For our 2048 app, we will add a "High Score" screen in React Native.
The first bit of code we will write is the actual React Native code for the new "High Score" screen that will be integrated into our application.
index.ios.js
file #First, create an empty index.ios.js
file. For ease, I am doing this in the root of the project.
index.ios.js
is the starting point for React Native applications on iOS. And it is always required. It can be a small file thatrequire
s other file that are part of your React Native component or application, or it can contain all the code that is needed for it. In our case, we will just put everything inindex.ios.js
In your index.ios.js
, create your component. In our sample here, we will add simple <Text>
component within a styled <View>
RNHighScores
is the name of your module that will be used when you add a view to React Native from within your iOS application.
RCTRootView
#Now that your React Native component is created via index.ios.js
, you need to add that component to a new or existing ViewController
. The easiest path to take is to optionally create an event path to your component and then add that component to an existing ViewController
.
We will tie our React Native component with a new native view in the ViewController
that will actually host it called RCTRootView
.
You can add a new link on the main game menu to go to the "High Score" React Native page.
We will now add an event handler from the menu link. A method will be added to the main ViewController
of your application. This is where RCTRootView
comes into play.
When you build a React Native application, you use the React Native packager to create an index.ios.bundle
that will be served by the React Native server. Inside index.ios.bundle
will be our RNHighScore
module. So, we need to point our RCTRootView
to the location of the index.ios.bundle
resource (via NSURL
) and tie it to the module.
We will, for debugging purposes, log that the event handler was invoked. Then, we will create a string with the location of our React Native code that exists inside the index.ios.bundle
. Finally, we will create the main RCTRootView
. Notice how we provide RNHighScores
as the moduleName
that we created above when writing the code for our React Native component.
First import
the RCTRootView
library.
The
initialProperties
are here for illustration purposes so we have some data for our high score screen. In our React Native component, we will usethis.props
to get access to that data.
Note that
RCTRootView initWithURL
starts up a new JSC VM. To save resources and simplify the communication between RN views in different parts of your native app, you can have multiple views powered by React Native that are associated with a single JS runtime. To do that, instead of using[RCTRootView alloc] initWithURL
, useRCTBridge initWithBundleURL
to create a bridge and then useRCTRootView initWithBridge
.
First import
the React
library.
The
initialProperties
are here for illustration purposes so we have some data for our high score screen. In our React Native component, we will usethis.props
to get access to that data.
Note that
RCTRootView bundleURL
starts up a new JSC VM. To save resources and simplify the communication between RN views in different parts of your native app, you can have multiple views powered by React Native that are associated with a single JS runtime. To do that, instead of usingRCTRootView bundleURL
, useRCTBridge initWithBundleURL
to create a bridge and then useRCTRootView initWithBridge
.
When moving your app to production, the
NSURL
can point to a pre-bundled file on disk via something like[[NSBundle mainBundle] URLForResource:@"main" withExtension:@"jsbundle"];
. You can use thereact-native-xcode.sh
script innode_modules/react-native/packager/
to generate that pre-bundled file.
When moving your app to production, the
NSURL
can point to a pre-bundled file on disk via something likelet mainBundle = NSBundle(URLForResource: "main" withExtension:"jsbundle")
. You can use thereact-native-xcode.sh
script innode_modules/react-native/packager/
to generate that pre-bundled file.
Wire up the new link in the main menu to the newly added event handler method.
One of the easier ways to do this is to open the view in the storyboard and right click on the new link. Select something such as the
Touch Up Inside
event, drag that to the storyboard and then select the created method from the list provided.
You have now done all the basic steps to integrate React Native with your current application. Now we will start the React Native packager to build the index.ios.bundle
packager and the server running on localhost
to serve it.
Apple has blocked implicit cleartext HTTP resource loading. So we need to add the following our project's Info.plist
(or equivalent) file.
If you are using Xcode or your favorite editor, build and run your native iOS application as normal. Alternatively, you can run the app from the command line using:
In our sample application, you should see the link to the "High Scores" and then when you click on that you will see the rendering of your React Native component.
Here is the native application home screen:
Here is the React Native high score screen:
If you are getting module resolution issues when running your application please see this GitHub issue for information and possible resolution. This comment seemed to be the latest possible resolution.
You can examine the code that added the React Native screen on GitHub.
You can examine the code that added the React Native screen on GitHub.
In your app's root folder, run:
This creates a node module for your app and adds the react-native
npm dependency. Now open the newly created package.json
file and add this under scripts
:
Copy & paste the following code to index.android.js
in your root folder — it's a barebones React Native app:
In your app's build.gradle
file add the React Native dependency:
In your project's build.gradle
file add an entry for the local React Native maven directory:
Next, make sure you have the Internet permission in your AndroidManifest.xml
:
This is only really used in dev mode when reloading JavaScript from the development server, so you can strip this in release builds if you need to.
You need to add some native code in order to start the React Native runtime and get it to render something. To do this, we're going to create an Activity
that creates a ReactRootView
, starts a React application inside it and sets it as the main content view.
We need set the theme of MyReactActivity
to Theme.AppCompat.Light.NoActionBar
beause some components rely on this theme.
A
ReactInstanceManager
can be shared amongst multiple activities and/or fragments. You will want to make your ownReactFragment
orReactActivity
and have a singleton holder that holds aReactInstanceManager
. When you need theReactInstanceManager
(e.g., to hook up theReactInstanceManager
to the lifecycle of those Activities or Fragments) use the one provided by the singleton.
Next, we need to pass some activity lifecycle callbacks down to the ReactInstanceManager
:
We also need to pass back button events to React Native:
This allows JavaScript to control what happens when the user presses the hardware back button (e.g. to implement navigation). When JavaScript doesn't handle a back press, your invokeDefaultOnBackPressed
method will be called. By default this simply finishes your Activity
.
Finally, we need to hook up the dev menu. By default, this is activated by (rage) shaking the device, but this is not very useful in emulators. So we make it show when you press the hardware menu button:
That's it, your activity is ready to run some JavaScript code.
To run your app, you need to first start the development server. To do this, simply run the following command in your root folder:
Now build and run your Android app as normal (e.g. ./gradlew installDebug
). Once you reach your React-powered activity inside the app, it should load the JavaScript code from the development server and display:
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