React NativeAccessibility
Native App Accessibility (iOS and Android) #
Both iOS and Android provide APIs for making apps accessible to people with disabilities. In addition, both platforms provide bundled assistive technologies, like the screen readers VoiceOver (iOS) and TalkBack (Android) for the visually impaired. Similarly, in React Native we have included APIs designed to provide developers with support for making apps more accessible. Take note, iOS and Android differ slightly in their approaches, and thus the React Native implementations may vary by platform.
Making Apps Accessible #
Accessibility properties #
accessible (iOS, Android) #
When true, indicates that the view is an accessibility element. When a view is an accessibility element, it groups its children into a single selectable component. By default, all touchable elements are accessible.
On Android, ‘accessible={true}’ property for a react-native View will be translated into native ‘focusable={true}’.
Accessibility # | Edit on GitHub |
Native App Accessibility (iOS and Android) #
Both iOS and Android provide APIs for making apps accessible to people with disabilities. In addition, both platforms provide bundled assistive technologies, like the screen readers VoiceOver (iOS) and TalkBack (Android) for the visually impaired. Similarly, in React Native we have included APIs designed to provide developers with support for making apps more accessible. Take note, iOS and Android differ slightly in their approaches, and thus the React Native implementations may vary by platform.
Making Apps Accessible #
Accessibility properties #
accessible (iOS, Android) #
When true, indicates that the view is an accessibility element. When a view is an accessibility element, it groups its children into a single selectable component. By default, all touchable elements are accessible.
On Android, ‘accessible={true}’ property for a react-native View will be translated into native ‘focusable={true}’.
In the above example, we can't get accessibility focus separately on 'text one' and 'text two'. Instead we get focus on a parent view with 'accessible' property.
accessibilityLabel (iOS, Android) #
When a view is marked as accessible, it is a good practice to set an accessibilityLabel on the view, so that people who use VoiceOver know what element they have selected. VoiceOver will read this string when a user selects the associated element.
To use, set the accessibilityLabel property to a custom string on your View:
ActionSheetIOS
Methods #
Edit on GitHubExamples #
ActionSheetIOS # | Edit on GitHub |
Methods #
Examples # | Edit on GitHub |
ActivityIndicatorIOS
Edit on GitHubProps #
animating bool #
Whether to show the indicator (true, the default) or hide it (false).
color string #
The foreground color of the spinner (default is gray).
hidesWhenStopped bool #
Whether the indicator should hide when not animating (true by default).
onLayout function #
Invoked on mount and layout changes with
{nativeEvent: { layout: {x, y, width, height}}}.
size enum('small', 'large') #
Size of the indicator. Small has a height of 20, large has a height of 36.
Edit on GitHubExamples #
ActivityIndicatorIOS # | Edit on GitHub |
Props #
animating bool #
Whether to show the indicator (true, the default) or hide it (false).
color string #
The foreground color of the spinner (default is gray).
hidesWhenStopped bool #
Whether the indicator should hide when not animating (true by default).
onLayout function #
Invoked on mount and layout changes with
{nativeEvent: { layout: {x, y, width, height}}}.
size enum('small', 'large') #
Size of the indicator. Small has a height of 20, large has a height of 36.
Examples # | Edit on GitHub |
Alert
Launches an alert dialog with the specified title and message.
Optionally provide a list of buttons. Tapping any button will fire the +
Alert # | Edit on GitHub |
Launches an alert dialog with the specified title and message.
Optionally provide a list of buttons. Tapping any button will fire the respective onPress callback and dismiss the alert. By default, the only button will be an 'OK' button.
This is an API that works both on iOS and Android and can show static
alerts. To show an alert that prompts the user to enter some information,
see AlertIOS; entering text in an alert is common on iOS only.
iOS #
On iOS you can specify any number of buttons. Each button can optionally
-specify a style and you can also specify type of the alert. Refer to
-AlertIOS for details.
Android #
On Android at most three buttons can be specified. Android has a concept +specify a style, which is one of 'default', 'cancel' or 'destructive'.
Android #
On Android at most three buttons can be specified. Android has a concept of a neutral, negative and a positive button:
- If you specify one button, it will be the 'positive' one (such as 'OK')
- Two buttons mean 'negative', 'positive' (such as 'Cancel', 'OK')
- Three buttons mean 'neutral', 'negative', 'positive' (such as 'Later', 'Cancel', 'OK')
- If you specify one butt {text: 'Cancel', onPress: () => console.log('Cancel Pressed'), style: 'cancel'}, {text: 'OK', onPress: () => console.log('OK Pressed')}, ] -)
Methods #
static alert(title: string, message?: string, buttons?: Buttons, type?: AlertType) #
Edit on GitHubExamples #
Methods #
static alert(title: string, message?: string, buttons?: Buttons, type?: AlertType) #
Examples # | Edit on GitHub |
- If you specify one butt module.exports = { AlertExample, SimpleAlertExampleBlock, -}
AlertIOS
Launches an alert dialog with the specified title and message.
Optionally provide a list of buttons. Tapping any button will fire the -respective onPress callback and dismiss the alert. By default, the only -button will be an 'OK' button.
Use this API for iOS-specific features, such as prompting the user to enter
-some information. In other cases, especially to show static alerts, use
-the cross-platform Alert API.
AlertIOS # | Edit on GitHub |
The AlertsIOS utility provides two functions: alert and prompt. All
+functionality available through AlertIOS.alert is also available in the
+cross-platform Alert.alert, which we recommend you use if you don't need
+iOS-specific functionality.
AlertIOS.prompt allows you to prompt the user for input inside of an
+alert popup.
Methods #
static alert(title: string, message?: string, callbackOrButtons?: ?(() => void) | ButtonsArray, type?: AlertType) #
Creates a popup to alert the user. See +Alert.
- title: string -- The dialog's title.
- message: string -- An optional message that appears above the text input.
callbackOrButtons -- This optional argument should be either a +single-argument function or an array of buttons. If passed a function, +it will be called when the user taps 'OK'.
If passed an array of button configurations, each button should include +a
textkey, as well as optionalonPressandstylekeys. +styleshould be one of 'default', 'cancel' or 'destructive'.- type -- deprecated, do not use
Example:
static prompt(title: string, message?: string, callbackOrButtons?: ?((text: string) => void) | ButtonsArray, type?: AlertType, defaultValue?: string) #
Prompt the user to enter some text.
- title: string -- The dialog's title.
- message: string -- An optional message that appears above the text input.
callbackOrButtons -- This optional argument should be either a +single-argument function or an array of buttons. If passed a function, +it will be called with the prompt's value when the user taps 'OK'.
If passed an array of button configurations, each button should include +a
textkey, as well as optionalonPressandstylekeys (see example). +styleshould be one of 'default', 'cancel' or 'destructive'.- type: string -- This configures the text input. One of 'plain-text', +'secure-text' or 'login-password'.
- defaultValue: string -- the default value for the text field.
Example with custom buttons:
Methods #
static alert(title: string, message?: string, buttons?: Array<{ - text?: string; - onPress?: ?Function; - style?: AlertButtonStyle; - }>, type?: AlertType) #
static prompt(title: string, value?: string, buttons?: Array<{ - text?: string; - onPress?: ?Function; - style?: AlertButtonStyle; - }>, callback?: Function) #
Prompt the user to enter some text.
Edit on GitHubRun this exampleExamples #
Example with the default button and a custom callback:
Examples # | Edit on GitHub |
Building React Native from source
You will need to build React Native from source if you want to work on a new feature/bug fix, try out the latest features which are not released yet, or maintain your own fork with patches that cannot be merged to the core.
Prerequisites #
Assuming you have the Android SDK installed, run android to open the Android SDK Manager.
Make sure you have the following installed:
- Android SDK version 23 (compileSdkVersion in
build.gradle) - SDK build tools version 23.0.1 (buildToolsVersion in
build.gradle) - Android Support Repository >= 17 (for Android Support Library)
- Android NDK (download & extraction instructions here)
Point Gradle to your Android SDK: either have $ANDROID_SDK and $ANDROID_NDK defined, or create a local.properties file in the root of your react-native checkout with the following contents:
Building React Native from source # | Edit on GitHub |
You will need to build React Native from source if you want to work on a new feature/bug fix, try out the latest features which are not released yet, or maintain your own fork with patches that cannot be merged to the core.
Prerequisites #
Assuming you have the Android SDK installed, run android to open the Android SDK Manager.
Make sure you have the following installed:
- Android SDK version 23 (compileSdkVersion in
build.gradle) - SDK build tools version 23.0.1 (buildToolsVersion in
build.gradle) - Android Support Repository >= 17 (for Android Support Library)
- Android NDK (download & extraction instructions here)
Point Gradle to your Android SDK: either have $ANDROID_SDK and $ANDROID_NDK defined, or create a local.properties file in the root of your react-native checkout with the following contents:
Example:
Building the source #
1. Installing the fork #
First, you need to install react-native from your fork. For example, to install the master branch from the official repo, run the following:
Alternatively, you can clone the repo to your node_modules directory and run npm install inside the cloned repo.
2. Adding gradle dependencies #
Add gradle-download-task as dependency in android/build.gradle:
Android Setup
This guide describes basic steps of the Android development environment setup that are required to run React Native android apps on an android emulator. We don't discuss developer tool configuration such as IDEs here.
Install Git #
On Mac, if you have installed XCode, Git is already installed, otherwise run the following:
brew install gitOn Linux, install Git via your package manager.
On Windows, download and install Git for Windows. During the setup process, choose "Run Git from Windows Command Prompt", which will add Git to your
PATHenvironment variable.
Install the Android SDK (unless you have it) #
- Install the latest JDK
- Install the Android SDK:
- On Mac:
brew install android-sdk - On Linux and Windows: Download from the Android website
- On Mac:
Define the ANDROID_HOME environment variable #
IMPORTANT: Make sure the ANDROID_HOME environment variable points to your existing Android SDK:
On Mac, add this to your
~/.bashrc,~/.bash_profileor whatever your shell uses:# If you installed the SDK via Homebrew, otherwise ~/Library/Android/sdk +Android Setup – React Native | A framework for building native apps using React Android Setup #
Edit on GitHub This guide describes basic steps of the Android development environment setup that are required to run React Native android apps on an android emulator. We don't discuss developer tool configuration such as IDEs here.
Install Git #
On Mac, if you have installed XCode, Git is already installed, otherwise run the following:
brew install gitOn Linux, install Git via your package manager.
On Windows, download and install Git for Windows. During the setup process, choose "Run Git from Windows Command Prompt", which will add Git to your
PATHenvironment variable.
Install the Android SDK (unless you have it) #
- Install the latest JDK
- Install the Android SDK:
- On Mac:
brew install android-sdk - On Linux and Windows: Download from the Android website
- On Mac:
Define the ANDROID_HOME environment variable #
IMPORTANT: Make sure the
ANDROID_HOMEenvironment variable points to your existing Android SDK:On Mac, add this to your
~/.bashrc,~/.bash_profileor whatever your shell uses:# If you installed the SDK via Homebrew, otherwise ~/Library/Android/sdk export ANDROID_HOME=/usr/local/opt/android-sdkOn Linux, add this to your
~/.bashrc,~/.bash_profileor whatever your shell uses:export ANDROID_HOME=<path_where_you_unpacked_android_sdk>On Windows, go to
Control Panel->System and Security->System->Change settings->Advanced->Environment variables->New
NOTE: You need to restart the Command Prompt (Windows) / Terminal Emulator (Mac OS X, Linux) to apply the new Environment variables.
Use gradle daemon #
React Native Android use gradle as a build system. We recommend to enable gradle daemon functionality which may result in up to 50% improvement in incremental build times for changes in java code. Learn here how to enable it for your platform.
Configure your SDK #
- Open the Android SDK Manager (on Mac start a new shell and run
android); in the window that appears make sure you check:- Android SDK Build-tools version 23.0.1
- Android 6.0 (API 23)
- Android Support Repository
- Click "Install Packages"
Install Genymotion #
Genymotion is much easier to set up than stock Google emulators. However, it's only free for personal use. If you want to use the stock Google emulator, see below.
- Download and install Genymotion.
- Open Genymotion. It might ask you to install VirtualBox unless you already have it.
- Create a new emulator and start it.
- To bring up the developer menu press ⌘+M
Alternative: Create a stock Google emulator #
- Start a new shell and run
android; in the window that appears make sure you check:- Intel x86 Atom System Image (for Android 5.1.1 - API 22)
- Intel x86 Emulator Accelerator (HAXM installer)
- Click "Install Packages".
- Configure hardware acceleration (HAXM), otherwise the emulator is going to be slow.
- Create an Android Virtual Device (AVD):
- Run
android avdand click on Create...
- With the new AVD selected, click
Start...
- Run
- To bring up the developer menu press F2 (or install Frappé)
Windows Hyper-V Alternative #
The Visual Studio Emulator for Android is a free android emulator that is hardware accelerated via Hyper-V. It doesn't require you to install Visual Studio at all.
To use it with react-native you just have to add a key and value to your registry:
- Open the Run Command (Windows+R)
- Enter
regedit.exe - In the Registry Editor navigate to
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Android SDK Tools - Right Click on
Android SDK Toolsand chooseNew > String Value - Set the name to
Path - Double Click the new
PathKey and set the value toC:\Program Files\Android\sdk. The path value might be different on your machine.
You will also need to run the command
adb reverse tcp:8081 tcp:8081with this emulator.Then restart the emulator and when it runs you can just do
react-native run-androidas usual.Profiling Android UI Performance
We try our best to deliver buttery-smooth UI performance by default, but sometimes that just isn't possible. Remember, Android supports 10k+ different phones and is generalized to support software rendering: the framework architecture and need to generalize across many hardware targets unfortunately means you get less for free relative to iOS. But sometimes, there are things you can improve (and many times it's not native code's fault at all!).
The first step for debugging this jank is to answer the fundamental question of where your time is being spent during each 16ms frame. For that, we'll be using a standard Android profiling tool called systrace. But first...
Make sure that JS dev mode is OFF!
You should see
__DEV__ === false, development-level warning are OFF, performance optimizations are ONin your application logs (which you can view usingadb logcat)Profiling with Systrace #
Systrace is a standard Android marker-based profiling tool (and is installed when you install the Android platform-tools package). Profiled code blocks are surrounded by markers start/end markers which are then visualized in a colorful chart format. Both the Android SDK and React Native framework provide standard markers that you can visualize.
Collecting a trace #
NOTE:
Systrace support was added in react-native
v0.15. You will need to build with that version to collect a trace.First, connect a device that exhibits the stuttering you want to investigate to your computer via USB and get it to the point right before the navigation/animation you want to profile. Run systrace as follows
$ <path_to_android_sdk>/platform-tools/systrace/systrace.py --time=10 -o trace.html sched gfx view -a <your_package_name>A quick breakdown of this command:
timeis the length of time the trace will be collected in secondssched,gfx, andvieware the android SDK tags (collections of markers) we care about:schedgives you information about what's running on each core of your phone,gfxgives you graphics info such as frame boundaries, andviewgives you information about measure, layout, and draw passes-a <your_package_name>enables app-specific markers, specifically the ones built into the React Native framework.your_package_namecan be found in theAndroidManifest.xmlof your app and looks likecom.example.app
Once the trace starts collecting, perform the animation or interaction you care about. At the end of the trace, systrace will give you a link to the trace which you can open in your browser.
Reading the trace #
After opening the trace in your browser (preferably Chrome), you should see something like this:
HINT: Use the WASD keys to strafe and zoom
Enable VSync highlighting #
The first thing you should do is highlight the 16ms frame boundaries if you haven't already done that. Check this checkbox at the top right of the screen:
You should see zebra stripes as in the screenshot above. If you don't, try profiling on a different device: Samsung has been known to have issues displaying vsyncs while the Nexus series is generally pretty reliable.
Find your process #
Scroll until you see (part of) the name of your package. In this case, I was profiling
com.facebook.adsmanager, which shows up asbook.adsmanagerbecause of silly thread name limits in the kernel.On the left side, you'll see a set of threads which correspond to the timeline rows on the right. There are three/four threads we care about for our purposes: the UI thread (which has your package name or the name UI Thread),
mqt_jsandmqt_native_modules. If you're running on Android 5+, we also care about the Render Thread.UI Thread #
This is where standard android measure/layout/draw happens. The thread name on the right will be your package name (in my case book.adsmanager) or UI Thread. The events that you see on this thread should look something like this and have to do with
Choreographer,traversals, andDispatchUI:
JS Thread #
This is where JS is executed. The thread name will be either
mqt_jsor<...>depending on how cooperative the kernel on your device is being. To identify it if it doesn't have a name, look for things likeJSCall,Bridge.executeJSCall, etc:
Native Modules Thread #
This is where native module calls (e.g. the
UIManager) are executed. The thread name will be eithermqt_native_modulesor<...>. To identify it in the latter case, look for things likeNativeCall,callJavaModuleMethod, andonBatchComplete:
Bonus: Render Thread #
If you're using Android L (5.0) and up, you will also have a render thread in your application. This thread generates the actual OpenGL commands used to draw your UI. The thread name will be either
RenderThreador<...>. To identify it in the latter case, look for things likeDrawFrameandqueueBuffer:
Identifying a culprit #
A smooth animation should look something like the following:
Each change in color is a frame -- remember that in order to display a frame, all our UI work needs to be done by the end of that 16ms period. Notice that no thread is working close to the frame boundary. An application rendering like this is rendering at 60FPS.
If you noticed chop, however, you might see something like this:
Notice that the JS thread is executing basically all the time, and across frame boundaries! This app is not rendering at 60FPS. In this case, the problem lies in JS.
You might also see something like this:
In this case, the UI and render threads are the ones that have work crossing frame boundaries. The UI that we're trying to render on each frame is requiring too much work to be done. In this case, the problem lies in the native views being rendered.
At this point, you'll have some very helpful information to inform your next steps.
JS Issues #
If you identified a JS problem, look for clues in the specific JS that you're executing. In the scenario above, we see
RCTEventEmitterbeing called multiple times per frame. Here's a zoom-in of the JS thread from the trace above:
This doesn't seem right. Why is it being called so often? Are they actually different events? The answers to these questions will probably depend on your product code. And many times, you'll want to look into shouldComponentUpdate.
TODO: Add more tools for profiling JS
Native UI Issues #
If you identified a native UI problem, there are usually two scenarios:
- the UI you're trying to draw each frame involves to much work on the GPU, or
- You're constructing new UI during the animation/interaction (e.g. loading in new content during a scroll).
Too much GPU work #
In the first scenario, you'll see a trace that has the UI thread and/or Render Thread looking like this:
Notice the long amount of time spent in
DrawFramethat crosses frame boundaries. This is time spent waiting for the GPU to drain its command buffer from the previous frame.To mitigate this, you should:
- investigate using
renderToHardwareTextureAndroidfor complex, static content that is being animated/transformed (e.g. theNavigatorslide/alpha animations) - make sure that you are not using
needsOffscreenAlphaCompositing, which is disabled by default, as it greatly increases the per-frame load on the GPU in most cases.
If these don't help and you want to dig deeper into what the GPU is actually doing, you can check out Tracer for OpenGL ES.
Creating new views on the UI thread #
In the second scenario, you'll see something more like this:
Notice that first the JS thread thinks for a bit, then you see some work done on the native modules thread, followed by an expensive traversal on the UI thread.
There isn't an easy way to mitigate this unless you're able to postpone creating new UI until after the interaction, or you are able to simplify the UI you're creating. The react native team is working on a infrastructure level solution for this that will allow new UI to be created and configured off the main thread, allowing the interaction to continue smoothly.
Still stuck? #
If you are confused or stuck, please post ask on Stack Overflow with the react-native tag. If you are unable to get a response there, or find an issue with a core component, please File a Github issue.
Profiling Android UI Performance #
Edit on GitHub We try our best to deliver buttery-smooth UI performance by default, but sometimes that just isn't possible. Remember, Android supports 10k+ different phones and is generalized to support software rendering: the framework architecture and need to generalize across many hardware targets unfortunately means you get less for free relative to iOS. But sometimes, there are things you can improve (and many times it's not native code's fault at all!).
The first step for debugging this jank is to answer the fundamental question of where your time is being spent during each 16ms frame. For that, we'll be using a standard Android profiling tool called systrace. But first...
Make sure that JS dev mode is OFF!
You should see
__DEV__ === false, development-level warning are OFF, performance optimizations are ONin your application logs (which you can view usingadb logcat)Profiling with Systrace #
Systrace is a standard Android marker-based profiling tool (and is installed when you install the Android platform-tools package). Profiled code blocks are surrounded by markers start/end markers which are then visualized in a colorful chart format. Both the Android SDK and React Native framework provide standard markers that you can visualize.
Collecting a trace #
NOTE:
Systrace support was added in react-native
v0.15. You will need to build with that version to collect a trace.First, connect a device that exhibits the stuttering you want to investigate to your computer via USB and get it to the point right before the navigation/animation you want to profile. Run systrace as follows
$ <path_to_android_sdk>/platform-tools/systrace/systrace.py --time=10 -o trace.html sched gfx view -a <your_package_name>A quick breakdown of this command:
timeis the length of time the trace will be collected in secondssched,gfx, andvieware the android SDK tags (collections of markers) we care about:schedgives you information about what's running on each core of your phone,gfxgives you graphics info such as frame boundaries, andviewgives you information about measure, layout, and draw passes-a <your_package_name>enables app-specific markers, specifically the ones built into the React Native framework.your_package_namecan be found in theAndroidManifest.xmlof your app and looks likecom.example.app
Once the trace starts collecting, perform the animation or interaction you care about. At the end of the trace, systrace will give you a link to the trace which you can open in your browser.
Reading the trace #
After opening the trace in your browser (preferably Chrome), you should see something like this:
HINT: Use the WASD keys to strafe and zoom
Enable VSync highlighting #
The first thing you should do is highlight the 16ms frame boundaries if you haven't already done that. Check this checkbox at the top right of the screen:
You should see zebra stripes as in the screenshot above. If you don't, try profiling on a different device: Samsung has been known to have issues displaying vsyncs while the Nexus series is generally pretty reliable.
Find your process #
Scroll until you see (part of) the name of your package. In this case, I was profiling
com.facebook.adsmanager, which shows up asbook.adsmanagerbecause of silly thread name limits in the kernel.On the left side, you'll see a set of threads which correspond to the timeline rows on the right. There are three/four threads we care about for our purposes: the UI thread (which has your package name or the name UI Thread),
mqt_jsandmqt_native_modules. If you're running on Android 5+, we also care about the Render Thread.UI Thread #
This is where standard android measure/layout/draw happens. The thread name on the right will be your package name (in my case book.adsmanager) or UI Thread. The events that you see on this thread should look something like this and have to do with
Choreographer,traversals, andDispatchUI:JS Thread #
This is where JS is executed. The thread name will be either
mqt_jsor<...>depending on how cooperative the kernel on your device is being. To identify it if it doesn't have a name, look for things likeJSCall,Bridge.executeJSCall, etc:Native Modules Thread #
This is where native module calls (e.g. the
UIManager) are executed. The thread name will be eithermqt_native_modulesor<...>. To identify it in the latter case, look for things likeNativeCall,callJavaModuleMethod, andonBatchComplete:Bonus: Render Thread #
If you're using Android L (5.0) and up, you will also have a render thread in your application. This thread generates the actual OpenGL commands used to draw your UI. The thread name will be either
RenderThreador<...>. To identify it in the latter case, look for things likeDrawFrameandqueueBuffer:Identifying a culprit #
A smooth animation should look something like the following:
Each change in color is a frame -- remember that in order to display a frame, all our UI work needs to be done by the end of that 16ms period. Notice that no thread is working close to the frame boundary. An application rendering like this is rendering at 60FPS.
If you noticed chop, however, you might see something like this:
Notice that the JS thread is executing basically all the time, and across frame boundaries! This app is not rendering at 60FPS. In this case, the problem lies in JS.
You might also see something like this:
In this case, the UI and render threads are the ones that have work crossing frame boundaries. The UI that we're trying to render on each frame is requiring too much work to be done. In this case, the problem lies in the native views being rendered.
At this point, you'll have some very helpful information to inform your next steps.
JS Issues #
If you identified a JS problem, look for clues in the specific JS that you're executing. In the scenario above, we see
RCTEventEmitterbeing called multiple times per frame. Here's a zoom-in of the JS thread from the trace above:This doesn't seem right. Why is it being called so often? Are they actually different events? The answers to these questions will probably depend on your product code. And many times, you'll want to look into shouldComponentUpdate.
TODO: Add more tools for profiling JS
Native UI Issues #
If you identified a native UI problem, there are usually two scenarios:
- the UI you're trying to draw each frame involves to much work on the GPU, or
- You're constructing new UI during the animation/interaction (e.g. loading in new content during a scroll).
Too much GPU work #
In the first scenario, you'll see a trace that has the UI thread and/or Render Thread looking like this:
Notice the long amount of time spent in
DrawFramethat crosses frame boundaries. This is time spent waiting for the GPU to drain its command buffer from the previous frame.To mitigate this, you should:
- investigate using
renderToHardwareTextureAndroidfor complex, static content that is being animated/transformed (e.g. theNavigatorslide/alpha animations) - make sure that you are not using
needsOffscreenAlphaCompositing, which is disabled by default, as it greatly increases the per-frame load on the GPU in most cases.
If these don't help and you want to dig deeper into what the GPU is actually doing, you can check out Tracer for OpenGL ES.
Creating new views on the UI thread #
In the second scenario, you'll see something more like this:
Notice that first the JS thread thinks for a bit, then you see some work done on the native modules thread, followed by an expensive traversal on the UI thread.
There isn't an easy way to mitigate this unless you're able to postpone creating new UI until after the interaction, or you are able to simplify the UI you're creating. The react native team is working on a infrastructure level solution for this that will allow new UI to be created and configured off the main thread, allowing the interaction to continue smoothly.
Still stuck? #
If you are confused or stuck, please post ask on Stack Overflow with the react-native tag. If you are unable to get a response there, or find an issue with a core component, please File a Github issue.
Animated
Animations are an important part of modern UX, and the
Animated+Animated – React Native | A framework for building native apps using React Animated #
Edit on GitHub Animations are an important part of modern UX, and the
Animatedlibrary is designed to make them fluid, powerful, and easy to build and maintain.The simplest workflow is to create an
Animated.Value, hook it up to one or more style attributes of an animated component, and then drive updates either @@ -124,7 +124,7 @@ API to normalAnimated.Value, but multiplexed. Contains two regula } }Methods #
constructor(valueIn?: ?{x: number | AnimatedValue; y: number | AnimatedValue}) #
setValue(value: {x: number; y: number}) #
setOffset(offset: {x: number; y: number}) #
flattenOffset() #
stopAnimation(callback?: ?() => number) #
addListener(callback: ValueXYListenerCallback) #
removeListener(id: string) #
getLayout() #
Converts
{x, y}into{left, top}for use in style, e.g.style={this.state.anim.getLayout()}getTranslateTransform() #
Converts
{x, y}into a useable translation transform, e.g.style={{ transform: this.state.anim.getTranslateTransform() - }}Edit on GitHubExamples #
'use strict'; + }}Examples #
Edit on GitHub 'use strict'; var React = require('react-native'); var { diff --git a/docs/animations.html b/docs/animations.html index f7f31148479..abc2955c772 100644 --- a/docs/animations.html +++ b/docs/animations.html @@ -1,4 +1,4 @@ -Animations – React Native | A framework for building native apps using React Animations
Fluid, meaningful animations are essential to the mobile user experience. Like +
Animations – React Native | A framework for building native apps using React Animations #
Edit on GitHub Fluid, meaningful animations are essential to the mobile user experience. Like everything in React Native, Animation APIs for React Native are currently under development, but have started to coalesce around two complementary systems:
LayoutAnimationfor animated global layout transactions, andAnimatedfor diff --git a/docs/appregistry.html b/docs/appregistry.html index 172f6736e27..befc28406bf 100644 --- a/docs/appregistry.html +++ b/docs/appregistry.html @@ -1,4 +1,4 @@ -AppRegistry – React Native | A framework for building native apps using React AppRegistry
AppRegistryis the JS entry point to running all React Native apps. App +AppRegistry – React Native | A framework for building native apps using React AppRegistry #
Edit on GitHub AppRegistryis the JS entry point to running all React Native apps. App root components should register themselves withAppRegistry.registerComponent, then the native system can load the bundle for the app and then actually run the app when it's ready by invoking diff --git a/docs/appstate.html b/docs/appstate.html index 10259477b6a..43a71f4fb78 100644 --- a/docs/appstate.html +++ b/docs/appstate.html @@ -1,4 +1,4 @@ -AppState – React Native | A framework for building native apps using React AppState
AppStatecan tell you if the app is in the foreground or background, +AppState – React Native | A framework for building native apps using React AppState #
Edit on GitHub AppStatecan tell you if the app is in the foreground or background, and notify you when the state changes.AppState is frequently used to determine the intent and proper behavior when handling push notifications.
App States #
active- The app is running in the foregroundbackground- The app is running in the background. The user is either in another app or on the home screeninactive- This is a transition state that currently never happens for @@ -26,10 +26,7 @@ render: funct },
This example will only ever appear to say "Current state is: active" because the app is only visible to the user when in the
activestate, and the null state will happen only momentarily.Methods #
Properties #
currentState: TypeCastExpression #
// TODO: getCurrentAppState callback seems to be called at a really late stage -// after app launch. Trying to get currentState when mounting App component -// will likely to have the initial value here. -// Initialize to 'active' instead of null.
Edit on GitHubExamples #
'use strict'; +and providing the handlerstatic removeEventListener(type: string, handler: Function) #
Remove a handler by passing the
changeevent type and the handlerProperties #
currentState: TypeCastExpression #
Examples #
Edit on GitHub 'use strict'; var React = require('react-native'); var { diff --git a/docs/appstateios.html b/docs/appstateios.html index 77c70ab734d..bd87e964562 100644 --- a/docs/appstateios.html +++ b/docs/appstateios.html @@ -1,4 +1,4 @@ -AppStateIOS – React Native | A framework for building native apps using React AppStateIOS
AppStateIOScan tell you if the app is in the foreground or background, +AppStateIOS – React Native | A framework for building native apps using React AppStateIOS #
Edit on GitHub AppStateIOScan tell you if the app is in the foreground or background, and notify you when the state changes.AppStateIOS is frequently used to determine the intent and proper behavior when handling push notifications.
iOS App States #
active- The app is running in the foregroundbackground- The app is running in the background. The user is either in another app or on the home screeninactive- This is a transition state that currently never happens for @@ -29,7 +29,7 @@ state will happen only momentarily.
static removeEventListener(type: string, handler: Function) #
Remove a handler by passing the
changeevent type and the handlerProperties #
currentState: TypeCastExpression #
// TODO: getCurrentAppState callback seems to be called at a really late stage // after app launch. Trying to get currentState when mounting App component // will likely to have the initial value here. -// Initialize to 'active' instead of null.
Edit on GitHubExamples #
'use strict'; +// Initialize to 'active' instead of null.Examples #
Edit on GitHub 'use strict'; var React = require('react-native'); var { diff --git a/docs/asyncstorage.html b/docs/asyncstorage.html index 59ce419bc4e..58fb3cd4bf6 100644 --- a/docs/asyncstorage.html +++ b/docs/asyncstorage.html @@ -1,4 +1,4 @@ -AsyncStorage – React Native | A framework for building native apps using React AsyncStorage
AsyncStorage is a simple, asynchronous, persistent, key-value storage +
AsyncStorage – React Native | A framework for building native apps using React AsyncStorage #
Edit on GitHub AsyncStorage is a simple, asynchronous, persistent, key-value storage system that is global to the app. It should be used instead of LocalStorage.
It is recommended that you use an abstraction on top of AsyncStorage instead of AsyncStorage directly for anything more than light usage since it operates globally.
This JS code is a simple facade over the native iOS implementation to provide @@ -11,7 +11,7 @@ don't want to call this - use removeItem or multiRemove to clear only your own keys instead. Returns a
Promiseobject.static getAllKeys(callback?: ?(error: ?Error, keys: ?Array<string>) => void) #
Gets all keys known to the app, for all callers, libraries, etc. Returns a
Promiseobject.static flushGetRequests() #
Flushes any pending requests using a single multiget
static multiGet(keys: Array<string>, callback?: ?(errors: ?Array<Error>, result: ?Array<Array<string>>) => void) #
multiGet invokes callback with an array of key-value pair arrays that matches the input format of multiSet. Returns a
Promiseobject.multiGet(['k1', 'k2'], cb) -> cb([['k1', 'val1'], ['k2', 'val2']])
static multiSet(keyValuePairs: Array<Array<string>>, callback?: ?(errors: ?Array<Error>) => void) #
multiSet and multiMerge take arrays of key-value array pairs that match the output of multiGet, e.g. Returns a
Promiseobject.multiSet([['k1', 'val1'], ['k2', 'val2']], cb);
static multiRemove(keys: Array<string>, callback?: ?(errors: ?Array<Error>) => void) #
Delete all the keys in the
keysarray. Returns aPromiseobject.static multiMerge(keyValuePairs: Array<Array<string>>, callback?: ?(errors: ?Array<Error>) => void) #
Merges existing values with input values, assuming they are stringified -json. Returns a
Promiseobject.Not supported by all native implementations.
Properties #
Edit on GitHubExamples #
'use strict'; +json. Returns aPromiseobject.Not supported by all native implementations.
Properties #
Examples #
Edit on GitHub 'use strict'; var React = require('react-native'); var { diff --git a/docs/backandroid.html b/docs/backandroid.html index 411242077da..c910c808f3b 100644 --- a/docs/backandroid.html +++ b/docs/backandroid.html @@ -1,4 +1,4 @@ -BackAndroid – React Native | A framework for building native apps using React BackAndroid
Detect hardware back button presses, and programmatically invoke the default back button +
BackAndroid – React Native | A framework for building native apps using React BackAndroid #
Edit on GitHub Detect hardware back button presses, and programmatically invoke the default back button functionality to exit the app if there are no listeners or if none of the listeners return true.
Example:
BackAndroid.addEventListener('hardwareBackPress', function() { if (!this.onMainScreen()) { this.goBack(); diff --git a/docs/cameraroll.html b/docs/cameraroll.html index f1c9fbe8446..cec8b395710 100644 --- a/docs/cameraroll.html +++ b/docs/cameraroll.html @@ -1,11 +1,6 @@ -CameraRoll – React Native | A framework for building native apps using React CameraRoll
CameraRollprovides access to the local camera roll / gallery.Methods #
static saveImageWithTag(tag, successCallback, errorCallback) #
Saves the image to the camera roll / gallery.
The CameraRoll API is not yet implemented for Android.
@param {string} tag On Android, this is a local URI, such -as
"file:///sdcard/img.png".On iOS, the tag can be one of the following:
- local URI
- assets-library tag
- a tag not matching any of the above, which means the image data will -be stored in memory (and consume memory as long as the process is alive)
@param successCallback Invoked with the value of
tagon success. -@param errorCallback Invoked with error message on error.static getPhotos(params, callback, errorCallback) #
Invokes
callbackwith photo identifier objects from the local camera - roll of the device matching shape defined bygetPhotosReturnChecker.@param {object} params See
getPhotosParamChecker. - @param {function} callback Invoked with arg of shape defined by -getPhotosReturnCheckeron success. - @param {function} errorCallback Invoked with error message on error.Edit on GitHubExamples #
'use strict'; +CameraRoll – React Native | A framework for building native apps using React CameraRoll #
Edit on GitHub CameraRollprovides access to the local camera roll / gallery.Methods #
static saveImageWithTag(tag) #
Saves the image to the camera roll / gallery.
On Android, the tag is a local URI, such as
"file:///sdcard/img.png".On iOS, the tag can be one of the following:
- local URI
- assets-library tag
- a tag not matching any of the above, which means the image data will +be stored in memory (and consume memory as long as the process is alive)
Returns a Promise which when resolved will be passed the new URI.
static getPhotos(params: object) #
Returns a Promise with photo identifier objects from the local camera +roll of the device matching shape defined by
getPhotosReturnChecker.@param {object} params See
getPhotosParamChecker.Returns a Promise which when resolved will be of shape
getPhotosReturnChecker.Examples #
Edit on GitHub 'use strict'; const React = require('react-native'); const { diff --git a/docs/colors.html b/docs/colors.html new file mode 100644 index 00000000000..8548910b80f --- /dev/null +++ b/docs/colors.html @@ -0,0 +1,12 @@ +Colors – React Native | A framework for building native apps using React \ No newline at end of file diff --git a/docs/communication-ios.html b/docs/communication-ios.html index 3b18b49eb11..a00135baf80 100644 --- a/docs/communication-ios.html +++ b/docs/communication-ios.html @@ -1,4 +1,4 @@ -Colors #
Edit on GitHub The following formats are supported:
#f0f(#rgb)#f0fc(#rgba)#ff00ff(#rrggbb)#ff00ff00(#rrggbbaa)rgb(255, 255, 255)rgba(255, 255, 255, 1.0)hsl(360, 100%, 100%)hsla(360, 100%, 100%, 1.0)transparentred
For the named colors, React Native follows the CSS3 specification:
- aliceblue (#f0f8ff)
- antiquewhite (#faebd7)
- aqua (#00ffff)
- aquamarine (#7fffd4)
- azure (#f0ffff)
- beige (#f5f5dc)
- bisque (#ffe4c4)
- black (#000000)
- blanchedalmond (#ffebcd)
- blue (#0000ff)
- blueviolet (#8a2be2)
- brown (#a52a2a)
- burlywood (#deb887)
- cadetblue (#5f9ea0)
- chartreuse (#7fff00)
- chocolate (#d2691e)
- coral (#ff7f50)
- cornflowerblue (#6495ed)
- cornsilk (#fff8dc)
- crimson (#dc143c)
- cyan (#00ffff)
- darkblue (#00008b)
- darkcyan (#008b8b)
- darkgoldenrod (#b8860b)
- darkgray (#a9a9a9)
- darkgreen (#006400)
- darkgrey (#a9a9a9)
- darkkhaki (#bdb76b)
- darkmagenta (#8b008b)
- darkolivegreen (#556b2f)
- darkorange (#ff8c00)
- darkorchid (#9932cc)
- darkred (#8b0000)
- darksalmon (#e9967a)
- darkseagreen (#8fbc8f)
- darkslateblue (#483d8b)
- darkslategray (#2f4f4f)
- darkslategrey (#2f4f4f)
- darkturquoise (#00ced1)
- darkviolet (#9400d3)
- deeppink (#ff1493)
- deepskyblue (#00bfff)
- dimgray (#696969)
- dimgrey (#696969)
- dodgerblue (#1e90ff)
- firebrick (#b22222)
- floralwhite (#fffaf0)
- forestgreen (#228b22)
- fuchsia (#ff00ff)
- gainsboro (#dcdcdc)
- ghostwhite (#f8f8ff)
- gold (#ffd700)
- goldenrod (#daa520)
- gray (#808080)
- green (#008000)
- greenyellow (#adff2f)
- grey (#808080)
- honeydew (#f0fff0)
- hotpink (#ff69b4)
- indianred (#cd5c5c)
- indigo (#4b0082)
- ivory (#fffff0)
- khaki (#f0e68c)
- lavender (#e6e6fa)
- lavenderblush (#fff0f5)
- lawngreen (#7cfc00)
- lemonchiffon (#fffacd)
- lightblue (#add8e6)
- lightcoral (#f08080)
- lightcyan (#e0ffff)
- lightgoldenrodyellow (#fafad2)
- lightgray (#d3d3d3)
- lightgreen (#90ee90)
- lightgrey (#d3d3d3)
- lightpink (#ffb6c1)
- lightsalmon (#ffa07a)
- lightseagreen (#20b2aa)
- lightskyblue (#87cefa)
- lightslategray (#778899)
- lightslategrey (#778899)
- lightsteelblue (#b0c4de)
- lightyellow (#ffffe0)
- lime (#00ff00)
- limegreen (#32cd32)
- linen (#faf0e6)
- magenta (#ff00ff)
- maroon (#800000)
- mediumaquamarine (#66cdaa)
- mediumblue (#0000cd)
- mediumorchid (#ba55d3)
- mediumpurple (#9370db)
- mediumseagreen (#3cb371)
- mediumslateblue (#7b68ee)
- mediumspringgreen (#00fa9a)
- mediumturquoise (#48d1cc)
- mediumvioletred (#c71585)
- midnightblue (#191970)
- mintcream (#f5fffa)
- mistyrose (#ffe4e1)
- moccasin (#ffe4b5)
- navajowhite (#ffdead)
- navy (#000080)
- oldlace (#fdf5e6)
- olive (#808000)
- olivedrab (#6b8e23)
- orange (#ffa500)
- orangered (#ff4500)
- orchid (#da70d6)
- palegoldenrod (#eee8aa)
- palegreen (#98fb98)
- paleturquoise (#afeeee)
- palevioletred (#db7093)
- papayawhip (#ffefd5)
- peachpuff (#ffdab9)
- peru (#cd853f)
- pink (#ffc0cb)
- plum (#dda0dd)
- powderblue (#b0e0e6)
- purple (#800080)
- rebeccapurple (#663399)
- red (#ff0000)
- rosybrown (#bc8f8f)
- royalblue (#4169e1)
- saddlebrown (#8b4513)
- salmon (#fa8072)
- sandybrown (#f4a460)
- seagreen (#2e8b57)
- seashell (#fff5ee)
- sienna (#a0522d)
- silver (#c0c0c0)
- skyblue (#87ceeb)
- slateblue (#6a5acd)
- slategray (#708090)
- slategrey (#708090)
- snow (#fffafa)
- springgreen (#00ff7f)
- steelblue (#4682b4)
- tan (#d2b48c)
- teal (#008080)
- thistle (#d8bfd8)
- tomato (#ff6347)
- turquoise (#40e0d0)
- violet (#ee82ee)
- wheat (#f5deb3)
- white (#ffffff)
- whitesmoke (#f5f5f5)
- yellow (#ffff00)
- yellowgreen (#9acd32)
Communication between native and React Native – React Native | A framework for building native apps using React Communication between native and React Native
In Integrating with Existing Apps guide and Native UI Components guide we learn how to embed React Native in a native component and vice versa. When we mix native and React Native components, we'll eventually find a need to communicate between these two worlds. Some ways to achieve that have been already mentioned in other guides. This article summarizes available techniques.
Introduction #
React Native is inspired by React, so the basic idea of the information flow is similar. The flow in React is one-directional. We maintain a hierarchy of components, in which each component depends only on its parent and own internal state. We do this with properties: data is passed from a parent to its children in a top-down manner. If we have an ancestor component that rely on the state of its descendant, the recommended solution would be to pass down a callback that would be used by the descendant to update the ancestor.
The same concept applies to React Native. As long as we are building our application purely within the framework, we can drive our app with properties and callbacks. But, when we mix React Native and native components, we need some special, cross-language mechanisms that would allow us to pass information between them.
Properties #
Properties are the simplest way of cross-component communication. So we need a way to pass properties both from native to React Native, and from React Native to native.
Passing properties from native to React Native #
In order to embed a React Native view in a native component, we use
RCTRootView.RCTRootViewis aUIViewthat holds a React Native app. It also provides an interface between native side and the hosted app.RCTRootViewhas an initializer that allows you to pass arbitrary properties down to the React Native app. TheinitialPropertiesparameter has to be an instance ofNSDictionary. The dictionary is internally converted into a JSON object that the top-level JS component can reference.NSArray *imageList = @[@"http://foo.com/bar1.png", +Communication between native and React Native – React Native | A framework for building native apps using React Communication between native and React Native #
Edit on GitHub In Integrating with Existing Apps guide and Native UI Components guide we learn how to embed React Native in a native component and vice versa. When we mix native and React Native components, we'll eventually find a need to communicate between these two worlds. Some ways to achieve that have been already mentioned in other guides. This article summarizes available techniques.
Introduction #
React Native is inspired by React, so the basic idea of the information flow is similar. The flow in React is one-directional. We maintain a hierarchy of components, in which each component depends only on its parent and own internal state. We do this with properties: data is passed from a parent to its children in a top-down manner. If we have an ancestor component that rely on the state of its descendant, the recommended solution would be to pass down a callback that would be used by the descendant to update the ancestor.
The same concept applies to React Native. As long as we are building our application purely within the framework, we can drive our app with properties and callbacks. But, when we mix React Native and native components, we need some special, cross-language mechanisms that would allow us to pass information between them.
Properties #
Properties are the simplest way of cross-component communication. So we need a way to pass properties both from native to React Native, and from React Native to native.
Passing properties from native to React Native #
In order to embed a React Native view in a native component, we use
RCTRootView.RCTRootViewis aUIViewthat holds a React Native app. It also provides an interface between native side and the hosted app.RCTRootViewhas an initializer that allows you to pass arbitrary properties down to the React Native app. TheinitialPropertiesparameter has to be an instance ofNSDictionary. The dictionary is internally converted into a JSON object that the top-level JS component can reference.NSArray *imageList = @[@"http://foo.com/bar1.png", @"http://foo.com/bar2.png"]; NSDictionary *props = @{@"images" : imageList}; diff --git a/docs/datepickerios.html b/docs/datepickerios.html index 21fa0d77502..df0c8dd35c9 100644 --- a/docs/datepickerios.html +++ b/docs/datepickerios.html @@ -1,12 +1,12 @@ -DatePickerIOS – React Native | A framework for building native apps using React DatePickerIOS
Use
DatePickerIOSto render a date/time picker (selector) on iOS. This is +DatePickerIOS – React Native | A framework for building native apps using React DatePickerIOS #
Edit on GitHub Use
DatePickerIOSto render a date/time picker (selector) on iOS. This is a controlled component, so you must hook in to theonDateChangecallback and update thedateprop in order for the component to update, otherwise the user's change will be reverted immediately to reflectprops.dateas the -source of truth.Edit on GitHubProps #
date Date #
The currently selected date.
maximumDate Date #
Maximum date.
Restricts the range of possible date/time values.
minimumDate Date #
Minimum date.
Restricts the range of possible date/time values.
minuteInterval enum(1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30) #
The interval at which minutes can be selected.
mode enum('date', 'time', 'datetime') #
The date picker mode.
onDateChange function #
Date change handler.
This is called when the user changes the date or time in the UI. +source of truth.
Props #
date Date #
The currently selected date.
maximumDate Date #
Maximum date.
Restricts the range of possible date/time values.
minimumDate Date #
Minimum date.
Restricts the range of possible date/time values.
minuteInterval enum(1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30) #
The interval at which minutes can be selected.
mode enum('date', 'time', 'datetime') #
The date picker mode.
onDateChange function #
Date change handler.
This is called when the user changes the date or time in the UI. The first and only argument is a Date object representing the new date and time.
timeZoneOffsetInMinutes number #
Timezone offset in minutes.
By default, the date picker will use the device's timezone. With this parameter, it is possible to force a certain timezone offset. For -instance, to show times in Pacific Standard Time, pass -7 * 60.
Edit on GitHubExamples #
'use strict'; +instance, to show times in Pacific Standard Time, pass -7 * 60.Examples #
Edit on GitHub 'use strict'; var React = require('react-native'); var { diff --git a/docs/debugging.html b/docs/debugging.html index ef3fdb543eb..216620e4adb 100644 --- a/docs/debugging.html +++ b/docs/debugging.html @@ -1,4 +1,4 @@ -Debugging – React Native | A framework for building native apps using React Debugging
Debugging React Native Apps #
To access the in-app developer menu:
- On iOS shake the device or press
control + ⌘ + zin the simulator. - On Android shake the device or press hardware menu button (available on older devices and in most of the emulators, e.g. in genymotion you can press
⌘ + mto simulate hardware menu button click). You can also install Frappé, a tool for OS X, which allows you to emulate shaking of devices remotely. You can use⌘ + Shift + Ras a shortcut to trigger a shake from Frappé.
Hint
To disable the developer menu for production builds:
- For iOS open your project in Xcode and select
Product→Scheme→Edit Scheme...(or press⌘ + <). Next, selectRunfrom the menu on the left and change the Build Configuration toRelease. - For Android, by default, developer menu will be disabled in release builds done by gradle (e.g with gradle
assembleReleasetask). Although this behavior can be customized by passing proper value toReactInstanceManager#setUseDeveloperSupport.
Reload #
Selecting
Reload(or pressing⌘ + rin the iOS simulator) will reload the JavaScript that powers your application. If you have added new resources (such as an image toImages.xcassetson iOS or tores/drawablefolder on Android) or modified any native code (Objective-C/Swift code on iOS or Java/C++ code on Android), you will need to re-build the app for the changes to take effect.Chrome Developer Tools #
To debug the JavaScript code in Chrome, select
Debug in Chromefrom the developer menu. This will open a new tab at http://localhost:8081/debugger-ui.In Chrome, press
⌘ + option + ior selectView→Developer→Developer Toolsto toggle the developer tools console. Enable Pause On Caught Exceptions for a better debugging experience.To debug on a real device:
- On iOS - open the file
RCTWebSocketExecutor.mand changelocalhostto the IP address of your computer. Shake the device to open the development menu with the option to start debugging. - On Android, if you're running Android 5.0+ device connected via USB you can use
adbcommand line tool to setup port forwarding from the device to your computer. For that run:adb reverse tcp:8081 tcp:8081(see this link for help onadbcommand). Alternatively, you can open dev menu on the device and selectDev Settings, then updateDebug server host for devicesetting to the IP address of your computer.
React Developer Tools (optional) #
Install the React Developer Tools extension for Google Chrome. This will allow you to navigate the component hierarchy via the
Reactin the developer tools (see facebook/react-devtools for more information).Live Reload #
This option allows for your JS changes to trigger automatic reload on the connected device/emulator. To enable this option:
- On iOS, select
Enable Live Reloadvia the developer menu to have the application automatically reload when changes are made to the JavaScript. - On Android, launch dev menu, go to
Dev Settingsand selectAuto reload on JS changeoption
FPS (Frames per Second) Monitor #
On
0.5.0-rcand higher versions, you can enable a FPS graph overlay in the developers menu in order to help you debug performance problems.Debugging #
Edit on GitHub Debugging React Native Apps #
To access the in-app developer menu:
- On iOS shake the device or press
control + ⌘ + zin the simulator. - On Android shake the device or press hardware menu button (available on older devices and in most of the emulators, e.g. in genymotion you can press
⌘ + mto simulate hardware menu button click). You can also install Frappé, a tool for OS X, which allows you to emulate shaking of devices remotely. You can use⌘ + Shift + Ras a shortcut to trigger a shake from Frappé.
Hint
To disable the developer menu for production builds:
- For iOS open your project in Xcode and select
Product→Scheme→Edit Scheme...(or press⌘ + <). Next, selectRunfrom the menu on the left and change the Build Configuration toRelease. - For Android, by default, developer menu will be disabled in release builds done by gradle (e.g with gradle
assembleReleasetask). Although this behavior can be customized by passing proper value toReactInstanceManager#setUseDeveloperSupport.
Reload #
Selecting
Reload(or pressing⌘ + rin the iOS simulator) will reload the JavaScript that powers your application. If you have added new resources (such as an image toImages.xcassetson iOS or tores/drawablefolder on Android) or modified any native code (Objective-C/Swift code on iOS or Java/C++ code on Android), you will need to re-build the app for the changes to take effect.Chrome Developer Tools #
To debug the JavaScript code in Chrome, select
Debug in Chromefrom the developer menu. This will open a new tab at http://localhost:8081/debugger-ui.In Chrome, press
⌘ + option + ior selectView→Developer→Developer Toolsto toggle the developer tools console. Enable Pause On Caught Exceptions for a better debugging experience.To debug on a real device:
- On iOS - open the file
RCTWebSocketExecutor.mand changelocalhostto the IP address of your computer. Shake the device to open the development menu with the option to start debugging. - On Android, if you're running Android 5.0+ device connected via USB you can use
adbcommand line tool to setup port forwarding from the device to your computer. For that run:adb reverse tcp:8081 tcp:8081(see this link for help onadbcommand). Alternatively, you can open dev menu on the device and selectDev Settings, then updateDebug server host for devicesetting to the IP address of your computer.
React Developer Tools (optional) #
Install the React Developer Tools extension for Google Chrome. This will allow you to navigate the component hierarchy via the
Reactin the developer tools (see facebook/react-devtools for more information).Live Reload #
This option allows for your JS changes to trigger automatic reload on the connected device/emulator. To enable this option:
- On iOS, select
Enable Live Reloadvia the developer menu to have the application automatically reload when changes are made to the JavaScript. - On Android, launch dev menu, go to
Dev Settingsand selectAuto reload on JS changeoption
FPS (Frames per Second) Monitor #
On
0.5.0-rcand higher versions, you can enable a FPS graph overlay in the developers menu in order to help you debug performance problems.Dimensions
Methods #
static set(dims: {[key:string]: any}) #
This should only be called from native code.
@param {object} dims Simple string-keyed object of dimensions to set
static get(dim: string) #
Initial dimensions are set before
runApplicationis called so they should +Dimensions – React Native | A framework for building native apps using React Dimensions #
Edit on GitHub Methods #
static set(dims: {[key:string]: any}) #
This should only be called from native code.
@param {object} dims Simple string-keyed object of dimensions to set
static get(dim: string) #
Initial dimensions are set before
runApplicationis called so they should be available before any other require's are run, but may be updated later.Note: Although dimensions are available immediately, they may change (e.g due to device rotation) so any rendering logic or styles that depend on these constants should try to call this function on every render, rather diff --git a/docs/direct-manipulation.html b/docs/direct-manipulation.html index ed17b582c25..43724de2cb3 100644 --- a/docs/direct-manipulation.html +++ b/docs/direct-manipulation.html @@ -1,4 +1,4 @@ -
Direct Manipulation – React Native | A framework for building native apps using React Direct Manipulation
It is sometimes necessary to make changes directly to a component +
Direct Manipulation – React Native | A framework for building native apps using React Direct Manipulation #
Edit on GitHub It is sometimes necessary to make changes directly to a component without using state/props to trigger a re-render of the entire subtree. When using React in the browser for example, you sometimes need to directly modify a DOM node, and the same is true for views in mobile diff --git a/docs/drawerlayoutandroid.html b/docs/drawerlayoutandroid.html index 49f9eb7070b..459c625c2d7 100644 --- a/docs/drawerlayoutandroid.html +++ b/docs/drawerlayoutandroid.html @@ -1,4 +1,4 @@ -
DrawerLayoutAndroid – React Native | A framework for building native apps using React DrawerLayoutAndroid
React component that wraps the platform
DrawerLayout(Android only). The +DrawerLayoutAndroid – React Native | A framework for building native apps using React DrawerLayoutAndroid #
Edit on GitHub React component that wraps the platform
DrawerLayout(Android only). The Drawer (typically used for navigation) is rendered withrenderNavigationViewand direct children are the main view (where your content goes). The navigation view is initially not visible on the screen, but can be pulled in from the @@ -20,8 +20,8 @@ be set by thedrawerWidthprop.Example:
/View> </DrawerLayoutAndroid> ); -},Edit on GitHubProps #
drawerPosition enum(DrawerConsts.DrawerPosition.Left, DrawerConsts.DrawerPosition.Right) #
Specifies the side of the screen from which the drawer will slide in.
drawerWidth number #
Specifies the width of the drawer, more precisely the width of the view that be pulled in -from the edge of the window.
keyboardDismissMode enum('none', "on-drag") #
Determines whether the keyboard gets dismissed in response to a drag. +},
Props #
drawerPosition enum(DrawerConsts.DrawerPosition.Left, DrawerConsts.DrawerPosition.Right) #
Specifies the side of the screen from which the drawer will slide in.
drawerWidth number #
Specifies the width of the drawer, more precisely the width of the view that be pulled in +from the edge of the window.
keyboardDismissMode enum('none', 'on-drag') #
Determines whether the keyboard gets dismissed in response to a drag. - 'none' (the default), drags do not dismiss the keyboard. - 'on-drag', the keyboard is dismissed when a drag begins.
onDrawerClose function #
Function called whenever the navigation view has been closed.
onDrawerOpen function #
Function called whenever the navigation view has been opened.
onDrawerSlide function #
Function called whenever there is an interaction with the navigation view.
onDrawerStateChanged function #
Function called when the drawer state has changed. The drawer can be in 3 states: - idle, meaning there is no interaction with the navigation view happening at the time diff --git a/docs/embedded-app-android.html b/docs/embedded-app-android.html index 922992a7ce1..229918c755c 100644 --- a/docs/embedded-app-android.html +++ b/docs/embedded-app-android.html @@ -1,4 +1,4 @@ -
Integrating with Existing Apps – React Native | A framework for building native apps using React Integrating with Existing Apps
Since React makes no assumptions about the rest of your technology stack, it's easily embeddable within an existing non-React Native app.
Requirements #
- an existing, gradle-based Android app
- Node.js, see Getting Started for setup instructions
Prepare your app #
In your app's
build.gradlefile add the React Native dependency:compile 'com.facebook.react:react-native:0.17.+'You can find the latest version of the react-native library on Maven Central. Next, make sure you have the Internet permission in your
AndroidManifest.xml:<uses-permission android:name="android.permission.INTERNET" />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.
Add native code #
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
Activitythat creates aReactRootView, starts a React application inside it and sets it as the main content view.public class MyReactActivity extends Activity implements DefaultHardwareBackBtnHandler { +Integrating with Existing Apps – React Native | A framework for building native apps using React Integrating with Existing Apps #
Edit on GitHub Since React makes no assumptions about the rest of your technology stack, it's easily embeddable within an existing non-React Native app.
Requirements #
- an existing, gradle-based Android app
- Node.js, see Getting Started for setup instructions
Prepare your app #
In your app's
build.gradlefile add the React Native dependency:compile 'com.facebook.react:react-native:0.17.+'You can find the latest version of the react-native library on Maven Central. Next, make sure you have the Internet permission in your
AndroidManifest.xml:<uses-permission android:name="android.permission.INTERNET" />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.
Add native code #
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
Activitythat creates aReactRootView, starts a React application inside it and sets it as the main content view.public class MyReactActivity extends Activity implements DefaultHardwareBackBtnHandler { private ReactRootView mReactRootView; private ReactInstanceManager mReactInstanceManager; diff --git a/docs/embedded-app-ios.html b/docs/embedded-app-ios.html index 68957763c2c..db8c4c5f7ff 100644 --- a/docs/embedded-app-ios.html +++ b/docs/embedded-app-ios.html @@ -1,4 +1,4 @@ -Integrating with Existing Apps – React Native | A framework for building native apps using React Integrating with Existing Apps
Since React makes no assumptions about the rest of your technology stack – it’s commonly noted as simply the
VinMVC– it’s easily embeddable within an existing non-React Native app. In fact, it integrates with other best practice community tools like CocoaPods.Requirements #
- CocoaPods –
gem install cocoapods - Node.js
- Install nvm with its setup instructions here. Then run
nvm install node && nvm alias default node, which installs the latest version of Node.js and sets up your terminal so you can run it by typingnode. With nvm you can install multiple versions of Node.js and easily switch between them.
- Install nvm with its setup instructions here. Then run
- Install the
react-nativepackage from npm by running the following command in the root directory of your project:npm install react-native
At this point you should have the React Native package installed under a directory named
node_modulesas a sibling to your.xcodeprojfile.Install React Native Using CocoaPods #
CocoaPods is a package management tool for iOS/Mac development. We need to use it to download React Native. If you haven't installed CocoaPods yet, check out this tutorial.
When you are ready to work with CocoaPods, add the following lines to
Podfile. If you don't have one, then create it under the root directory of your project.# Depending on how your project is organized, your node_modules directory may be +Integrating with Existing Apps – React Native | A framework for building native apps using React Integrating with Existing Apps #
Edit on GitHub Since React makes no assumptions about the rest of your technology stack – it’s commonly noted as simply the
VinMVC– it’s easily embeddable within an existing non-React Native app. In fact, it integrates with other best practice community tools like CocoaPods.Requirements #
- CocoaPods –
gem install cocoapods - Node.js
- Install nvm with its setup instructions here. Then run
nvm install node && nvm alias default node, which installs the latest version of Node.js and sets up your terminal so you can run it by typingnode. With nvm you can install multiple versions of Node.js and easily switch between them.
- Install nvm with its setup instructions here. Then run
- Install the
react-nativepackage from npm by running the following command in the root directory of your project:npm install react-native
At this point you should have the React Native package installed under a directory named
node_modulesas a sibling to your.xcodeprojfile.Install React Native Using CocoaPods #
CocoaPods is a package management tool for iOS/Mac development. We need to use it to download React Native. If you haven't installed CocoaPods yet, check out this tutorial.
When you are ready to work with CocoaPods, add the following lines to
Podfile. If you don't have one, then create it under the root directory of your project.# Depending on how your project is organized, your node_modules directory may be # somewhere else; tell CocoaPods where you've installed react-native from npm pod 'React', :path => './node_modules/react-native', :subspecs => [ 'Core', diff --git a/docs/flexbox.html b/docs/flexbox.html index 310080d63ab..f1c9114723d 100644 --- a/docs/flexbox.html +++ b/docs/flexbox.html @@ -1,4 +1,4 @@ -Flexbox – React Native | A framework for building native apps using React Flexbox
Edit on GitHubProps #
alignItems enum('flex-start', 'flex-end', 'center', 'stretch') #
alignSelf enum('auto', 'flex-start', 'flex-end', 'center', 'stretch') #
borderBottomWidth number #
borderLeftWidth number #
borderRightWidth number #
borderTopWidth number #
borderWidth number #
bottom number #
flex number #
flexDirection enum('row', 'column') #
flexWrap enum('wrap', 'nowrap') #
height number #
justifyContent enum('flex-start', 'flex-end', 'center', 'space-between', 'space-around') #
left number #
margin number #
marginBottom number #
marginHorizontal number #
marginLeft number #
marginRight number #
marginTop number #
marginVertical number #
maxHeight number #
maxWidth number #
minHeight number #
minWidth number #
padding number #
paddingBottom number #
paddingHorizontal number #
paddingLeft number #
paddingRight number #
paddingTop number #
paddingVertical number #
position enum('absolute', 'relative') #
right number #
top number #
width number #
Flexbox #
Edit on GitHub Props #
alignItems enum('flex-start', 'flex-end', 'center', 'stretch') #
alignSelf enum('auto', 'flex-start', 'flex-end', 'center', 'stretch') #
borderBottomWidth number #
borderLeftWidth number #
borderRightWidth number #
borderTopWidth number #
borderWidth number #
bottom number #
flex number #
flexDirection enum('row', 'column') #
flexWrap enum('wrap', 'nowrap') #
height number #
justifyContent enum('flex-start', 'flex-end', 'center', 'space-between', 'space-around') #
left number #
margin number #
marginBottom number #
marginHorizontal number #
marginLeft number #
marginRight number #
marginTop number #
marginVertical number #
padding number #
paddingBottom number #
paddingHorizontal number #
paddingLeft number #
paddingRight number #
paddingTop number #
paddingVertical number #
position enum('absolute', 'relative') #
right number #
top number #
width number #
Geolocation
The Geolocation API follows the web spec: +
Geolocation – React Native | A framework for building native apps using React Geolocation #
Edit on GitHub The Geolocation API follows the web spec: https://developer.mozilla.org/en-US/docs/Web/API/Geolocation
iOS #
You need to include the
NSLocationWhenInUseUsageDescriptionkey in Info.plist to enable geolocation. Geolocation is enabled by default when you create a project withreact-native init.Android #
To request access to location, you need to add the following line to your app's
AndroidManifest.xml:<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />Methods #
static getCurrentPosition(geo_success: Function, geo_error?: Function, geo_options?: GeoOptions) #
Invokes the success callback once with the latest location info. Supported options: timeout (ms), maximumAge (ms), enableHighAccuracy (bool)
static watchPosition(success: Function, error?: Function, options?: GeoOptions) #
Invokes the success callback whenever the location changes. Supported -options: timeout (ms), maximumAge (ms), enableHighAccuracy (bool)
static clearWatch(watchID: number) #
static stopObserving() #
Edit on GitHubExamples #
/* eslint no-console: 0 */ +options: timeout (ms), maximumAge (ms), enableHighAccuracy (bool)static clearWatch(watchID: number) #
static stopObserving() #
Examples #
Edit on GitHub /* eslint no-console: 0 */ 'use strict'; diff --git a/docs/gesture-responder-system.html b/docs/gesture-responder-system.html index b57f09f6d2c..f481883f3f1 100644 --- a/docs/gesture-responder-system.html +++ b/docs/gesture-responder-system.html @@ -1,4 +1,4 @@ -Gesture Responder System – React Native | A framework for building native apps using React Gesture Responder System
Gesture recognition on mobile devices is much more complicated than web. A touch can go through several phases as the app determines what the user's intention is. For example, the app needs to determine if the touch is scrolling, sliding on a widget, or tapping. This can even change during the duration of a touch. There can also be multiple simultaneous touches.
The touch responder system is needed to allow components to negotiate these touch interactions without any additional knowledge about their parent or child components. This system is implemented in
ResponderEventPlugin.js, which contains further details and documentation.Best Practices #
Users can feel huge differences in the usability of web apps vs. native, and this is one of the big causes. Every action should have the following attributes:
- Feedback/highlighting- show the user what is handling their touch, and what will happen when they release the gesture
- Cancel-ability- when making an action, the user should be able to abort it mid-touch by dragging their finger away
These features make users more comfortable while using an app, because it allows people to experiment and interact without fear of making mistakes.
TouchableHighlight and Touchable* #
The responder system can be complicated to use. So we have provided an abstract
Touchableimplementation for things that should be "tappable". This uses the responder system and allows you to easily configure tap interactions declaratively. UseTouchableHighlightanywhere where you would use a button or link on web.Responder Lifecycle #
A view can become the touch responder by implementing the correct negotiation methods. There are two methods to ask the view if it wants to become responder:
View.props.onStartShouldSetResponder: (evt) => true,- Does this view want to become responder on the start of a touch?View.props.onMoveShouldSetResponder: (evt) => true,- Called for every touch move on the View when it is not the responder: does this view want to "claim" touch responsiveness?
If the View returns true and attempts to become the responder, one of the following will happen:
View.props.onResponderGrant: (evt) => {}- The View is now responding for touch events. This is the time to highlight and show the user what is happeningView.props.onResponderReject: (evt) => {}- Something else is the responder right now and will not release it
If the view is responding, the following handlers can be called:
View.props.onResponderMove: (evt) => {}- The user is moving their fingerView.props.onResponderRelease: (evt) => {}- Fired at the end of the touch, ie "touchUp"View.props.onResponderTerminationRequest: (evt) => true- Something else wants to become responder. Should this view release the responder? Returning true allows releaseView.props.onResponderTerminate: (evt) => {}- The responder has been taken from the View. Might be taken by other views after a call toonResponderTerminationRequest, or might be taken by the OS without asking (happens with control center/ notification center on iOS)
evtis a synthetic touch event with the following form:nativeEventchangedTouches- Array of all touch events that have changed since the last eventidentifier- The ID of the touchlocationX- The X position of the touch, relative to the elementlocationY- The Y position of the touch, relative to the elementpageX- The X position of the touch, relative to the root elementpageY- The Y position of the touch, relative to the root elementtarget- The node id of the element receiving the touch eventtimestamp- A time identifier for the touch, useful for velocity calculationtouches- Array of all current touches on the screen
Capture ShouldSet Handlers #
onStartShouldSetResponderandonMoveShouldSetResponderare called with a bubbling pattern, where the deepest node is called first. That means that the deepest component will become responder when multiple Views return true for*ShouldSetResponderhandlers. This is desirable in most cases, because it makes sure all controls and buttons are usable.However, sometimes a parent will want to make sure that it becomes responder. This can be handled by using the capture phase. Before the responder system bubbles up from the deepest component, it will do a capture phase, firing
on*ShouldSetResponderCapture. So if a parent View wants to prevent the child from becoming responder on a touch start, it should have aonStartShouldSetResponderCapturehandler which returns true.View.props.onStartShouldSetResponderCapture: (evt) => true,View.props.onMoveShouldSetResponderCapture: (evt) => true,
PanResponder #
For higher-level gesture interpretation, check out PanResponder.
Gesture Responder System #
Edit on GitHub Gesture recognition on mobile devices is much more complicated than web. A touch can go through several phases as the app determines what the user's intention is. For example, the app needs to determine if the touch is scrolling, sliding on a widget, or tapping. This can even change during the duration of a touch. There can also be multiple simultaneous touches.
The touch responder system is needed to allow components to negotiate these touch interactions without any additional knowledge about their parent or child components. This system is implemented in
ResponderEventPlugin.js, which contains further details and documentation.Best Practices #
Users can feel huge differences in the usability of web apps vs. native, and this is one of the big causes. Every action should have the following attributes:
- Feedback/highlighting- show the user what is handling their touch, and what will happen when they release the gesture
- Cancel-ability- when making an action, the user should be able to abort it mid-touch by dragging their finger away
These features make users more comfortable while using an app, because it allows people to experiment and interact without fear of making mistakes.
TouchableHighlight and Touchable* #
The responder system can be complicated to use. So we have provided an abstract
Touchableimplementation for things that should be "tappable". This uses the responder system and allows you to easily configure tap interactions declaratively. UseTouchableHighlightanywhere where you would use a button or link on web.Responder Lifecycle #
A view can become the touch responder by implementing the correct negotiation methods. There are two methods to ask the view if it wants to become responder:
View.props.onStartShouldSetResponder: (evt) => true,- Does this view want to become responder on the start of a touch?View.props.onMoveShouldSetResponder: (evt) => true,- Called for every touch move on the View when it is not the responder: does this view want to "claim" touch responsiveness?
If the View returns true and attempts to become the responder, one of the following will happen:
View.props.onResponderGrant: (evt) => {}- The View is now responding for touch events. This is the time to highlight and show the user what is happeningView.props.onResponderReject: (evt) => {}- Something else is the responder right now and will not release it
If the view is responding, the following handlers can be called:
View.props.onResponderMove: (evt) => {}- The user is moving their fingerView.props.onResponderRelease: (evt) => {}- Fired at the end of the touch, ie "touchUp"View.props.onResponderTerminationRequest: (evt) => true- Something else wants to become responder. Should this view release the responder? Returning true allows releaseView.props.onResponderTerminate: (evt) => {}- The responder has been taken from the View. Might be taken by other views after a call toonResponderTerminationRequest, or might be taken by the OS without asking (happens with control center/ notification center on iOS)
evtis a synthetic touch event with the following form:nativeEventchangedTouches- Array of all touch events that have changed since the last eventidentifier- The ID of the touchlocationX- The X position of the touch, relative to the elementlocationY- The Y position of the touch, relative to the elementpageX- The X position of the touch, relative to the root elementpageY- The Y position of the touch, relative to the root elementtarget- The node id of the element receiving the touch eventtimestamp- A time identifier for the touch, useful for velocity calculationtouches- Array of all current touches on the screen
Capture ShouldSet Handlers #
onStartShouldSetResponderandonMoveShouldSetResponderare called with a bubbling pattern, where the deepest node is called first. That means that the deepest component will become responder when multiple Views return true for*ShouldSetResponderhandlers. This is desirable in most cases, because it makes sure all controls and buttons are usable.However, sometimes a parent will want to make sure that it becomes responder. This can be handled by using the capture phase. Before the responder system bubbles up from the deepest component, it will do a capture phase, firing
on*ShouldSetResponderCapture. So if a parent View wants to prevent the child from becoming responder on a touch start, it should have aonStartShouldSetResponderCapturehandler which returns true.View.props.onStartShouldSetResponderCapture: (evt) => true,View.props.onMoveShouldSetResponderCapture: (evt) => true,
PanResponder #
For higher-level gesture interpretation, check out PanResponder.
Getting Started
Requirements #
- OS X - This guide assumes OS X which is needed for iOS development.
- Homebrew is the recommended way to install Watchman and Flow.
- Install Node.js 4.0 or newer.
- Install nvm with its setup instructions here. Then run
nvm install node && nvm alias default node, which installs the latest version of Node.js and sets up your terminal so you can run it by typingnode. With nvm you can install multiple versions of Node.js and easily switch between them. - New to npm?
- Install nvm with its setup instructions here. Then run
brew install watchman. We recommend installing watchman, otherwise you might hit a node file watching bug.brew install flow, if you want to use flow.
We recommend periodically running
brew update && brew upgradeto keep your programs up-to-date.iOS Setup #
Xcode 7.0 or higher is required. It can be installed from the App Store.
Android Setup #
To write React Native apps for Android, you will need to install the Android SDK (and an Android emulator if you want to work on your app without having to use a physical device). See Android setup guide for instructions on how to set up your Android environment.
NOTE: There is experimental Windows and Linux support for Android development.
Quick start #
$ npm install -g react-native-cli +Getting Started – React Native | A framework for building native apps using React Getting Started #
Edit on GitHub Requirements #
- OS X - This guide assumes OS X which is needed for iOS development.
- Homebrew is the recommended way to install Watchman and Flow.
- Install Node.js 4.0 or newer.
- Install nvm with its setup instructions here. Then run
nvm install node && nvm alias default node, which installs the latest version of Node.js and sets up your terminal so you can run it by typingnode. With nvm you can install multiple versions of Node.js and easily switch between them. - New to npm?
- Install nvm with its setup instructions here. Then run
brew install watchman. We recommend installing watchman, otherwise you might hit a node file watching bug.brew install flow, if you want to use flow.
We recommend periodically running
brew update && brew upgradeto keep your programs up-to-date.iOS Setup #
Xcode 7.0 or higher is required. It can be installed from the App Store.
Android Setup #
To write React Native apps for Android, you will need to install the Android SDK (and an Android emulator if you want to work on your app without having to use a physical device). See Android setup guide for instructions on how to set up your Android environment.
NOTE: There is experimental Windows and Linux support for Android development.
Quick start #
$ npm install -g react-native-cli $ react-native init AwesomeProjectTo run the iOS app:
$ cd AwesomeProject- Open
ios/AwesomeProject.xcodeprojand hit run in Xcode. - Open
index.ios.jsin your text editor of choice and edit some lines. - Hit ⌘-R in your iOS simulator to reload the app and see your change!
Note: If you are using an iOS device, see the Running on iOS Device page.
To run the Android app:
$ cd AwesomeProject$ react-native run-android- Open
index.android.jsin your text editor of choice and edit some lines. - Press the menu button (F2 by default, or ⌘-M in Genymotion) and select Reload JS to see your change!
- Run
adb logcat *:S ReactNative:V ReactNativeJS:Vin a terminal to see your app's logs
Note: If you are using an Android device, see the Running on Android Device page.
Congratulations! You've successfully run and modified your first React Native app.
If you run into any issues getting started, see the troubleshooting page.
Adding Android to an existing React Native project #
If you already have a (iOS-only) React Native project and want to add Android support, you need to execute the following commands in your existing project directory:
- Update the
react-nativedependency in yourpackage.jsonfile to the latest version $ npm install$ react-native android
Image
A React component for displaying different types of images, +
Image – React Native | A framework for building native apps using React Image #
Edit on GitHub A React component for displaying different types of images, including network images, static resources, temporary local images, and images from local disk, such as the camera roll.
Example usage:
renderImages: function() { return ( @@ -13,7 +13,7 @@ images from local disk, such as the camera roll.Example usage:
/> </View> ); -},Edit on GitHubProps #
onLayout function #
Invoked on mount and layout changes with +},
Props #
onLayout function #
Invoked on mount and layout changes with
{nativeEvent: {layout: {x, y, width, height}}}.onLoad function #
Invoked when load completes successfully
onLoadEnd function #
Invoked when load either succeeds or fails
onLoadStart function #
Invoked on load start
resizeMode enum('cover', 'contain', 'stretch') #
Determines how to resize the image when the frame doesn't match the raw image dimensions.
'cover': Scale the image uniformly (maintain the image's aspect ratio) so that both dimensions (width and height) of the image will be equal @@ -22,13 +22,22 @@ so that both dimensions (width and height) of the image will be equal to or less than the corresponding dimension of the view (minus padding).
'stretch': Scale width and height independently, This may change the aspect ratio of the src.
source {uri: string}, number #
uriis a string representing the resource identifier for the image, which could be an http address, a local file path, or the name of a static image -resource (which should be wrapped in therequire('./path/to/image.png')function).style style #
resizeMode Object.keys(ImageResizeMode)
backfaceVisibility enum('visible', 'hidden')
backgroundColor ColorPropType
borderColor ColorPropType
borderWidth number
borderRadius number
overflow enum('visible', 'hidden')
tintColor ColorPropType
opacity number
testID string #
A unique identifier for this element to be used in UI Automation +resource (which should be wrapped in the
require('./path/to/image.png')function).style style #
backfaceVisibility enum('visible', 'hidden')
backgroundColor color
borderColor color
borderRadius number
borderWidth number
opacity number
overflow enum('visible', 'hidden')
resizeMode Object.keys(ImageResizeMode)
androidoverlayColor string
When the image has rounded corners, specifying an overlayColor will +cause the remaining space in the corners to be filled with a solid color. +This is useful in cases which are not supported by the Android +implementation of rounded corners: + - Certain resize modes, such as 'contain' + - Animated GIFs
A typical way to use this prop is with images displayed on a solid +background and setting the
overlayColorto the same color +as the background.For details of how this works under the hood, see +http://frescolib.org/docs/rounded-corners-and-circles.html
iostintColor color
iOS-Specific style to "tint" an image. +Changes the color of all the non-transparent pixels to the tintColor.
testID string #
A unique identifier for this element to be used in UI Automation testing scripts.
iosaccessibilityLabel string #
The text that's read by the screen reader when the user interacts with the image.
iosaccessible bool #
When true, indicates the image is an accessibility element.
ioscapInsets {top: number, left: number, bottom: number, right: number} #
When the image is resized, the corners of the size specified by capInsets will stay a fixed size, but the center content and borders of the image will be stretched. This is useful for creating resizable rounded buttons, shadows, and other resizable assets. More info on -Apple documentation
iosdefaultSource {uri: string}, number #
A static image to display while loading the image source.
iosonError function #
Invoked on load error with
{nativeEvent: {error}}iosonProgress function #
Invoked on download progress with
{nativeEvent: {loaded, total}}Edit on GitHubExamples #
iosdefaultSource {uri: string}, number #
A static image to display while loading the image source.
iosonError function #
Invoked on load error with
{nativeEvent: {error}}iosonProgress function #
Invoked on download progress with
{nativeEvent: {loaded, total}}Examples #
Edit on GitHub 'use strict'; var React = require('react-native'); var { @@ -163,15 +172,15 @@ exports.examples }, { title: 'Plain Static Image', - description: 'Static assets should be required by prefixing with `image!` ' + - 'and are located in the app bundle.', + description: 'Static assets should be placed in the source code tree, and ' + + 'required in the same way as JavaScript modules.', render: function() { return ( <View style={styles.horizontal}> - <Image source={require('image!uie_thumb_normal')} style={styles.icon} /> - <Image source={require('image!uie_thumb_selected')} style={styles.icon} /> - <Image source={require('image!uie_comment_normal')} style={styles.icon} /> - <Image source={require('image!uie_comment_highlighted')} style={styles.icon} /> + <Image source={require('./uie_thumb_normal.png')} style={styles.icon} /> + <Image source={require('./uie_thumb_selected.png')} style={styles.icon} /> + <Image source={require('./uie_comment_normal.png')} style={styles.icon} /> + <Image source={require('./uie_comment_highlighted.png')} style={styles.icon} /> </View> ); }, @@ -202,6 +211,20 @@ exports.examples }, platform: 'ios', }, + { + title: 'defaultSource', + description: 'Show a placeholder image when a network image is loading', + render: function() { + return ( + <Image + defaultSource={require('./bunny.png')} + source={{uri: 'http://facebook.github.io/origami/public/images/birds.jpg'}} + style={styles.base} + /> + ); + }, + platform: 'ios', + }, { title: 'Border Color', render: function() { @@ -335,19 +358,19 @@ exports.examples > <View style={styles.horizontal}> <Image - source={require('image!uie_thumb_normal')} + source={require('./uie_thumb_normal.png')} style={[styles.icon, {borderRadius: 5, tintColor: '#5ac8fa' }]} /> <Image - source={require('image!uie_thumb_normal')} + source={require('./uie_thumb_normal.png')} style={[styles.icon, styles.leftMargin, {borderRadius: 5, tintColor: '#4cd964' }]} /> <Image - source={require('image!uie_thumb_normal')} + source={require('./uie_thumb_normal.png')} style={[styles.icon, styles.leftMargin, {borderRadius: 5, tintColor: '#ff2d55' }]} /> <Image - source={require('image!uie_thumb_normal')} + source={require('./uie_thumb_normal.png')} style={[styles.icon, styles.leftMargin, {borderRadius: 5, tintColor: '#8e8e93' }]} /> </View> diff --git a/docs/images.html b/docs/images.html index 8e54b3ea74b..4e5e53f93a8 100644 --- a/docs/images.html +++ b/docs/images.html @@ -1,4 +1,4 @@ -Images – React Native | A framework for building native apps using React Images
Static Image Resources #
As of 0.14 release, React Native provides a unified way of managing images in your iOS and Android apps. To add a static image to your app, place it somewhere in your source code tree and reference it like this:
<Image source={require('./my-icon.png')} />The image name is resolved the same way JS modules are resolved. In the example above the packager will look for
my-icon.pngin the same folder as the component that requires it. Also if you havemy-icon.ios.pngandmy-icon.android.png, the packager will pick the file depending on the platform you are running on.You can also use
@2x,@3x, etc. suffix in the file name to provide images for different screen densities. For example, if you have the following file structure:. +Images – React Native | A framework for building native apps using React Images #
Edit on GitHub Static Image Resources #
As of 0.14 release, React Native provides a unified way of managing images in your iOS and Android apps. To add a static image to your app, place it somewhere in your source code tree and reference it like this:
<Image source={require('./my-icon.png')} />The image name is resolved the same way JS modules are resolved. In the example above the packager will look for
my-icon.pngin the same folder as the component that requires it. Also if you havemy-icon.ios.pngandmy-icon.android.png, the packager will pick the file depending on the platform you are running on.You can also use
@2x,@3x, etc. suffix in the file name to provide images for different screen densities. For example, if you have the following file structure:. ├── button.js └── img ├── check@2x.png diff --git a/docs/intentandroid.html b/docs/intentandroid.html index bf7900d2346..5ec4b6e8e0b 100644 --- a/docs/intentandroid.html +++ b/docs/intentandroid.html @@ -1,12 +1,25 @@ -IntentAndroid – React Native | A framework for building native apps using React IntentAndroid
IntentAndroidgives you a general interface to handle external links.Basic Usage #
Handling deep links #
If your app was launched from an external url registered to your app you can +
IntentAndroid – React Native | A framework for building native apps using React IntentAndroid #
Edit on GitHub NOTE:
IntentAndroidis being deprecated. UseLinkinginstead.IntentAndroidgives you a general interface to handle external links.Basic Usage #
Handling deep links #
If your app was launched from an external url registered to your app you can access and handle it from any component you want with
componentDidMount() { var url = IntentAndroid.getInitialURL(url => { if (url) { console.log('Initial url is: ' + url); } }); -}NOTE: For instructions on how to add support for deep linking, -refer Enabling Deep Links for App Content - Add Intent Filters for Your Deep Links.
Opening external links #
To start the corresponding activity for a link (web URL, email, contact etc.), call
IntentAndroid.openURL(url)If you want to check if any installed app can handle a given URL beforehand you can call
IntentAndroid.canOpenURL(url, (supported) => { +}Example to add support for deep linking inside your React Native app. +More Info: Enabling Deep Links for App Content - Add Intent Filters for Your Deep Links.
Edit in
android/app/src/main/AndroidManifest.xml<intent-filter> + <action android:name="android.intent.action.VIEW" /> + <category android:name="android.intent.category.DEFAULT" /> + <category android:name="android.intent.category.BROWSABLE" /> + + <!-- Accepts URIs that begin with "http://www.facebook.com/react --> + <data android:scheme="http" + android:host="www.facebook.com" + android:pathPrefix="/react" /> + <!-- note that the leading "/" is required for pathPrefix--> + + <!-- Accepts URIs that begin with "facebook://react --> + <!-- <data android:scheme="facebook" android:host="react" /> --> + </intent-filter>Opening external links #
To start the corresponding activity for a link (web URL, email, contact etc.), call
IntentAndroid.openURL(url)If you want to check if any installed app can handle a given URL beforehand you can call
IntentAndroid.canOpenURL(url, (supported) => { if (!supported) { console.log('Can\'t handle url: ' + url); } else { @@ -15,9 +28,9 @@ refer });Methods #
static openURL(url: string) #
Starts a corresponding external activity for the given URL.
For example, if the URL is "https://www.facebook.com", the system browser will be opened, or the "choose application" dialog will be shown.
You can use other URLs, like a location (e.g. "geo:37.484847,-122.148386"), a contact, or any other URL that can be opened with {@code Intent.ACTION_VIEW}.
NOTE: This method will fail if the system doesn't know how to open the specified URL. -If you're passing in a non-http(s) URL, it's best to check {@code canOpenURL} first.
NOTE: For web URLs, the protocol ("http://", "https://") must be set accordingly!
static canOpenURL(url: string, callback: Function) #
Determine whether or not an installed app can handle a given URL.
You can use other URLs, like a location (e.g. "geo:37.484847,-122.148386"), a contact, -or any other URL that can be opened with {@code Intent.ACTION_VIEW}.
NOTE: For web URLs, the protocol ("http://", "https://") must be set accordingly!
@param URL the URL to open
static getInitialURL(callback: Function) #
If the app launch was triggered by an app link with {@code Intent.ACTION_VIEW}, -it will give the link url, otherwise it will give
nullRefer http://developer.android.com/training/app-indexing/deep-linking.html#handling-intents
Edit on GitHubExamples #
'use strict'; +If you're passing in a non-http(s) URL, it's best to check {@code canOpenURL} first.NOTE: For web URLs, the protocol ("http://", "https://") must be set accordingly!
@deprecated
static canOpenURL(url: string, callback: Function) #
Determine whether or not an installed app can handle a given URL.
You can use other URLs, like a location (e.g. "geo:37.484847,-122.148386"), a contact, +or any other URL that can be opened with {@code Intent.ACTION_VIEW}.
NOTE: For web URLs, the protocol ("http://", "https://") must be set accordingly!
@param URL the URL to open
@deprecated
static getInitialURL(callback: Function) #
If the app launch was triggered by an app link with {@code Intent.ACTION_VIEW}, +it will give the link url, otherwise it will give
nullRefer http://developer.android.com/training/app-indexing/deep-linking.html#handling-intents
@deprecated
Examples #
Edit on GitHub 'use strict'; var React = require('react-native'); var { diff --git a/docs/interactionmanager.html b/docs/interactionmanager.html index 8f0e7cc8794..eba00be8b68 100644 --- a/docs/interactionmanager.html +++ b/docs/interactionmanager.html @@ -1,4 +1,4 @@ -InteractionManager – React Native | A framework for building native apps using React InteractionManager
InteractionManager allows long-running work to be scheduled after any +
InteractionManager – React Native | A framework for building native apps using React InteractionManager #
Edit on GitHub InteractionManager allows long-running work to be scheduled after any interactions/animations have completed. In particular, this allows JavaScript animations to run smoothly.
Applications can schedule tasks to run after interactions with the following:
InteractionManager.runAfterInteractions(() => { // ...long-running synchronous task... diff --git a/docs/javascript-environment.html b/docs/javascript-environment.html index 54c21e43df5..c1764cb8e10 100644 --- a/docs/javascript-environment.html +++ b/docs/javascript-environment.html @@ -1,4 +1,4 @@ -JavaScript Environment – React Native | A framework for building native apps using React JavaScript Environment
JavaScript Runtime #
When using React Native, you're going to be running your JavaScript code in two environments:
- On iOS simulators and devices, Android emulators and devices React Native uses JavaScriptCore which is the JavaScript engine that powers Safari. On iOS JSC doesn't use JIT due to the absence of writable executable memory in iOS apps.
- When using Chrome debugging, it runs all the JavaScript code within Chrome itself and communicates with native code via WebSocket. So you are using V8.
While both environments are very similar, you may end up hitting some inconsistencies. We're likely going to experiment with other JS engines in the future, so it's best to avoid relying on specifics of any runtime.
JavaScript Syntax Transformers #
Syntax transformers make writing code more enjoyable by allowing you to use new JavaScript syntax without having to wait for support on all interpreters.
As of version 0.5.0, React Native ships with the Babel JavaScript compiler. Check Babel documentation on its supported transformations for more details.
Here's a full list of React Native's enabled transformations.
ES5
- Reserved Words:
promise.catch(function() { });
ES6
- Arrow functions:
<C onPress={() => this.setState({pressed: true})} - Block scoping:
let greeting = 'hi'; - Call spread:
Math.max(...array); - Classes:
class C extends React.Component { render() { return <View />; } } - Constants:
const answer = 42; - Destructuring:
var {isActive, style} = this.props; - Modules:
import React, { Component } from 'react-native'; - Computed Properties:
var key = 'abc'; var obj = {[key]: 10}; - Object Consise Method:
var obj = { method() { return 10; } }; - Object Short Notation:
var name = 'vjeux'; var obj = { name }; - Rest Params:
function(type, ...args) { } - Template Literals:
var who = 'world'; var str = `Hello ${who}`;
ES7
- Object Spread:
var extended = { ...obj, a: 10 }; - Function Trailing Comma:
function f(a, b, c,) { } - Async Functions:
async function doStuffAsync() { const foo = await doOtherStuffAsync(); };
JavaScript Environment #
Edit on GitHub JavaScript Runtime #
When using React Native, you're going to be running your JavaScript code in two environments:
- On iOS simulators and devices, Android emulators and devices React Native uses JavaScriptCore which is the JavaScript engine that powers Safari. On iOS JSC doesn't use JIT due to the absence of writable executable memory in iOS apps.
- When using Chrome debugging, it runs all the JavaScript code within Chrome itself and communicates with native code via WebSocket. So you are using V8.
While both environments are very similar, you may end up hitting some inconsistencies. We're likely going to experiment with other JS engines in the future, so it's best to avoid relying on specifics of any runtime.
JavaScript Syntax Transformers #
Syntax transformers make writing code more enjoyable by allowing you to use new JavaScript syntax without having to wait for support on all interpreters.
As of version 0.5.0, React Native ships with the Babel JavaScript compiler. Check Babel documentation on its supported transformations for more details.
Here's a full list of React Native's enabled transformations.
ES5
- Reserved Words:
promise.catch(function() { });
ES6
- Arrow functions:
<C onPress={() => this.setState({pressed: true})} - Block scoping:
let greeting = 'hi'; - Call spread:
Math.max(...array); - Classes:
class C extends React.Component { render() { return <View />; } } - Constants:
const answer = 42; - Destructuring:
var {isActive, style} = this.props; - Modules:
import React, { Component } from 'react-native'; - Computed Properties:
var key = 'abc'; var obj = {[key]: 10}; - Object Consise Method:
var obj = { method() { return 10; } }; - Object Short Notation:
var name = 'vjeux'; var obj = { name }; - Rest Params:
function(type, ...args) { } - Template Literals:
var who = 'world'; var str = `Hello ${who}`;
ES7
- Object Spread:
var extended = { ...obj, a: 10 }; - Function Trailing Comma:
function f(a, b, c,) { } - Async Functions:
async function doStuffAsync() { const foo = await doOtherStuffAsync(); };
Known Issues
Devtools "React" Tab Does Not Work #
It's currently not possible to use the "React" tab in the devtools to inspect app widgets. This is due to a change in how the application scripts are evaluated in the devtools plugin; they are now run inside a Web Worker, and the plugin is unaware of this and so unable to communicate properly with React Native.
However, you can still use the Console feature of the devtools, and debugging JavaScript with breakpoints works too. To use the console, make sure to select the
⚙debuggerWorker.jsentry in the devtools dropdown that by default is set to<top frame>.Missing Modules and Native Views #
This is an initial release of React Native Android and therefore not all of the views present on iOS are released on Android. We are very much interested in the communities' feedback on the next set of modules and views for Open Source. Not all native views between iOS and Android have a 100% equivalent representation, here it will be necessary to use a counterpart eg using ProgressBar on Android in place of ActivityIndicator on iOS.
Our provisional plan for common views and modules includes:
Views #
Maps +Known Issues – React Native | A framework for building native apps using React