React NativeAccessibility # | 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}’.
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 # | Edit on GitHub |
Methods #
static showActionSheetWithOptions(options, callback) #
Display an iOS action sheet. The options object must contain one or more
+
ActionSheetIOS # | Edit on GitHub |
Methods #
static showActionSheetWithOptions(options, callback) #
Display an iOS action sheet. The options object must contain one or more
of:
options(array of strings) - a list of button titles (required)cancelButtonIndex(int) - index of cancel button inoptionsdestructiveButtonIndex(int) - index of destructive button inoptionstitle(string) - a title to show above the action sheetmessage(string) - a message to show below the title
static showShareActionSheetWithOptions(options, failureCallback, successCallback) #
Display the iOS share sheet. The options object should contain
-one or both of:
message(string) - a message to shareurl(string) - a URL to share
NOTE: if url points to a local file, or is a base64-encoded
+one or both of message and url and can additionally have
+a subject or excludedActivityTypes:
url(string) - a URL to sharemessage(string) - a message to sharesubject(string) - a subject for the messageexcludedActivityTypes(array) - the activites to exclude from the ActionSheet
NOTE: if url points to a local file, or is a base64-encoded
uri, the file it points to will be loaded and shared directly.
-In this way, you can share images, videos, PDF files, etc.
Examples # | Edit on GitHub |
Examples # | Edit on GitHub |
ActivityIndicator # | Edit on GitHub |
Displays a circular loading indicator.
Props #
animating bool #
Whether to show the indicator (true, the default) or hide it (false).
size enum('small', 'large') #
Size of the indicator. Small has a height of 20, large has a height of 36. +Other sizes can be obtained using a scale transform.
ioshidesWhenStopped bool #
Whether the indicator should hide when not animating (true by default).
Examples # | Edit on GitHub |
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 # | 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 +
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, @@ -13,7 +13,7 @@ of a neutral, negative and a positive button:
- 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, message?, buttons?, type?) #
Examples # | Edit on GitHub |
Methods #
static alert(title, message?, buttons?, type?) #
Examples # | Edit on GitHub |
AlertIOS # | Edit on GitHub |
The AlertsIOS utility provides two functions: alert and prompt. All
+
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
@@ -29,7 +29,7 @@ a text key, as well as optional onPress and styl
text => console.log("Your username is "+text),
null,
'default'
-)
Examples # | Edit on GitHub |
Examples # | Edit on GitHub |
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) - Local Maven repository for Support Libraries (formerly
Android Support Repository) >= 17 (for Android Support Library) - Android NDK (download links and installation instructions below)
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) - Local Maven repository for Support Libraries (formerly
Android Support Repository) >= 17 (for Android Support Library) - Android NDK (download links and installation instructions below)
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:
Download links for Android NDK #
- Mac OS (64-bit) - http://dl.google.com/android/repository/android-ndk-r10e-darwin-x86_64.zip
- Linux (64-bit) - http://dl.google.com/android/repository/android-ndk-r10e-linux-x86_64.zip
- Windows (64-bit) - http://dl.google.com/android/repository/android-ndk-r10e-windows-x86_64.zip
- Windows (32-bit) - http://dl.google.com/android/repository/android-ndk-r10e-windows-x86.zip
You can find further instructions on the official page.
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:
Testing #
If you made changes to React Native and submit a pull request, all tests will run on your pull request automatically. To run the tests locally, see Testing.
Troubleshooting #
Gradle build fails in ndk-build. See the section about local.properties file above.
We are planning improvements to the React Native documentation. Your responses to this short survey will go a long way in helping us provide valuable content. Thank you!
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
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 as book.adsmanager because 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_js and mqt_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, and DispatchUI:
JS Thread #
This is where JS is executed. The thread name will be either mqt_js or <...> depending on how cooperative the kernel on your device is being. To identify it if it doesn't have a name, look for things like JSCall, Bridge.executeJSCall, etc:
Native Modules Thread #
This is where native module calls (e.g. the UIManager) are executed. The thread name will be either mqt_native_modules or <...>. To identify it in the latter case, look for things like NativeCall, callJavaModuleMethod, and onBatchComplete:
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 RenderThread or <...>. To identify it in the latter case, look for things like DrawFrame and queueBuffer:
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 RCTEventEmitter being 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 DrawFrame that 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.
We are planning improvements to the React Native documentation. Your responses to this short survey will go a long way in helping us provide valuable content. Thank you!
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
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 as book.adsmanager because 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_js and mqt_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, and DispatchUI:
JS Thread #
This is where JS is executed. The thread name will be either mqt_js or <...> depending on how cooperative the kernel on your device is being. To identify it if it doesn't have a name, look for things like JSCall, Bridge.executeJSCall, etc:
Native Modules Thread #
This is where native module calls (e.g. the UIManager) are executed. The thread name will be either mqt_native_modules or <...>. To identify it in the latter case, look for things like NativeCall, callJavaModuleMethod, and onBatchComplete:
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 RenderThread or <...>. To identify it in the latter case, look for things like DrawFrame and queueBuffer:
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 RCTEventEmitter being 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 DrawFrame that 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.
We are planning improvements to the React Native documentation. Your responses to this short survey will go a long way in helping us provide valuable content. Thank you!
Animated # | Edit on GitHub |
Animations are an important part of modern UX, and the Animated
+
Animated # | Edit on GitHub |
Animations are an important part of modern UX, and the Animated
library 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
@@ -125,7 +125,7 @@ API to normal Animated.Value, but multiplexed. Contains two regula
}
}
Methods #
constructor(valueIn?) #
setValue(value) #
setOffset(offset) #
flattenOffset() #
stopAnimation(callback?) #
addListener(callback) #
removeListener(id) #
getLayout() #
Converts {x, y} into {left, top} for use in style, e.g.
getTranslateTransform() #
Converts {x, y} into a useable translation transform, e.g.
Examples # | Edit on GitHub |
Examples # | Edit on GitHub |
Animations # | Edit on GitHub |
Fluid, meaningful animations are essential to the mobile user experience. Like +
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:
LayoutAnimation for animated global layout transactions, and Animated for
@@ -186,7 +186,7 @@ familiar with. It accepts a function as its only argument and calls that
function before the next repaint. It is an essential building block for
animations that underlies all of the JavaScript-based animation APIs. In
general, you shouldn't need to call this yourself - the animation APIs will
-manage frame updates for you.
react-tween-state (Not recommended - use Animated instead) #
react-tween-state is a +manage frame updates for you.
react-tween-state (Not recommended - use Animated instead) #
react-tween-state is a minimal library that does exactly what its name suggests: it tweens a value in a component's state, starting at a from value and ending at a to value. This means that it generates the values in between those @@ -235,7 +235,7 @@ class App extends .onClass(App, tweenState.Mixin);
Here we animated the opacity, but as you might guess, we can animate any numeric value. Read more about react-tween-state in its -README.
Rebound (Not recommended - use Animated instead) #
Rebound.js is a JavaScript port of +README.
Rebound (Not recommended - use Animated instead) #
Rebound.js is a JavaScript port of Rebound for Android. It is similar in concept to react-tween-state: you have an initial value and set an end value, then Rebound generates intermediate values that you can @@ -391,6 +391,6 @@ source.
AppRegistry # | Edit on GitHub |
AppRegistry is the JS entry point to running all React Native apps. App
+
AppRegistry # | Edit on GitHub |
AppRegistry is the JS entry point to running all React Native apps. App
root components should register themselves with
AppRegistry.registerComponent, then the native system can load the bundle
for the app and then actually run the app when it's ready by invoking
@@ -6,7 +6,7 @@ for the app and then actually run the app when it's ready by invoking
AppRegistry.unmountApplicationComponentAtRootTag with the tag that was
pass into runApplication. These should always be used as a pair.
AppRegistry should be required early in the require sequence to make
sure the JS execution environment is setup before other modules are
-required.
Methods #
AppState # | Edit on GitHub |
AppState can tell you if the app is in the foreground or background,
+
AppState # | Edit on GitHub |
AppState can 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 - typical React Native apps.
For more information, see + in another app or on the home screen
inactive - This is a state that occurs when transitioning between
+ foreground & background, and during periods of inactivity such as
+ entering the Multitasking view or in the event of an incoming callFor more information, see Apple's documentation
Basic Usage #
To see the current state, you can check AppState.currentState, which
will be kept up-to-date. However, currentState will be null at launch
while AppState retrieves it over the bridge.
This example will only ever appear to say "Current state is: active" because
the app is only visible to the user when in the active state, and the null
-state will happen only momentarily.
Methods #
Properties #
currentState: TypeCastExpression #
Examples # | Edit on GitHub |
Methods #
constructor() #
addEventListener(type, handler) #
Add a handler to AppState changes by listening to the change event type
+and providing the handler
TODO: now that AppState is a subclass of NativeEventEmitter, we could deprecate
+addEventListener and removeEventListener and just use addListener and
+listener.remove() directly. That will be a breaking change though, as both
+the method and event names are different (addListener events are currently
+required to be globally unique).
removeEventListener(type, handler) #
Remove a handler by passing the change event type and the handler
Examples # | Edit on GitHub |
return { appState: AppState.currentState, previousAppStates: [], + memoryWarnings: 0, }; }, componentDidMount: function() { AppState.addEventListener('change', this._handleAppStateChange); + AppState.addEventListener('memoryWarning', this._handleMemoryWarning); }, componentWillUnmount: function() { AppState.removeEventListener('change', this._handleAppStateChange); + AppState.removeEventListener('memoryWarning', this._handleMemoryWarning); + }, + _handleMemoryWarning: function() { + this.setState({memoryWarnings: this.state.memoryWarnings + 1}); }, _handleAppStateChange: function(appState) { var previousAppStates = this.state.previousAppStates.slice(); @@ -58,6 +69,13 @@ and providing the handler
}); }, render() { + if (this.props.showMemoryWarnings) { + return ( + <View> + <Text>{this.state.memoryWarnings}</Text> + </View> + ); + } if (this.props.showCurrentOnly) { return ( <View> @@ -84,11 +102,17 @@ exports.examples { title: 'Subscribed AppState:', description: 'This changes according to the current state, so you can only ever see it rendered as "active"', - render(): ReactElement { return <AppStateSubscription showCurrentOnly={true} />; } + render(): ReactElement<any> { return <AppStateSubscription showCurrentOnly={true} />; } }, { title: 'Previous states:', - render(): ReactElement { return <AppStateSubscription showCurrentOnly={false} />; } + render(): ReactElement<any> { return <AppStateSubscription showCurrentOnly={false} />; } + }, + { + platform: 'ios', + title: 'Memory Warnings', + description: 'In the IOS simulator, hit Shift+Command+M to simulate a memory warning.', + render(): ReactElement<any> { return <AppStateSubscription showMemoryWarnings={true} />; } }, ];
AppStateIOS # | Edit on GitHub |
AppStateIOS can 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 state that occurs when transitioning between - foreground & background, and during periods of inactivity such as - entering the Multitasking view or in the event of an incoming call
For more information, see -Apple's documentation
Basic Usage #
To see the current state, you can check AppStateIOS.currentState, which
-will be kept up-to-date. However, currentState will be null at launch
-while AppStateIOS retrieves it over the bridge.
This example will only ever appear to say "Current state is: active" because
-the app is only visible to the user when in the active state, 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.
Examples # | Edit on GitHub |
AsyncStorage # | Edit on GitHub |
AsyncStorage is a simple, asynchronous, persistent, key-value storage +
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.
On iOS, AsyncStorage is backed by native code that stores small values in a serialized
@@ -20,7 +20,7 @@ Returns a Promise object. Not supported by all native implementatio
traits: {eyes: 'blue', shoe_size: 10}
};
-AsyncStorage.setItem(store_key, JSON.stringify(UID123_object), () => {
+AsyncStorage.setItem('UID123', JSON.stringify(UID123_object), () => {
AsyncStorage.mergeItem('UID123', JSON.stringify(UID123_delta), () => {
AsyncStorage.getItem('UID123', (err, result) => {
console.log(result);
@@ -85,7 +85,7 @@ AsyncStorage. });
});
});
-});
Properties #
Examples # | Edit on GitHub |
Properties #
Examples # | Edit on GitHub |
BackAndroid # | Edit on GitHub |
Detect hardware back button presses, and programmatically invoke the default back button +
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:
CameraRoll # | Edit on GitHub |
CameraRoll provides 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
+
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) #
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'; +roll of the device matching shape defined bygetPhotosReturnChecker.@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'); const ReactNative = require('react-native'); @@ -124,7 +124,7 @@ exports.description .examples = [ { title: 'Photos', - render(): ReactElement { return <CameraRollExample />; } + render(): ReactElement<any> { return <CameraRollExample />; } } ];
Clipboard # | Edit on GitHub |
Clipboard gives you an interface for setting and getting content from Clipboard on both iOS and Android
Methods #
static getString() #
Get content of string type, this method returns a Promise, so you can use following code to get clipboard content
Clipboard # | Edit on GitHub |
Clipboard gives you an interface for setting and getting content from Clipboard on both iOS and Android
Methods #
static getString() #
Get content of string type, this method returns a Promise, so you can use following code to get clipboard content
static setString(content) #
Set content of string type. You can use following code to set clipboard content
@param the content to be stored in the clipboard.
Examples # | Edit on GitHub |
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)''transparent''red'0xff00ff00(0xrrggbbaa)
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)
We are planning improvements to the React Native documentation. Your responses to this short survey will go a long way in helping us provide valuable content. Thank you!
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)''transparent''red'0xff00ff00(0xrrggbbaa)
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)
We are planning improvements to the React Native documentation. Your responses to this short survey will go a long way in helping us provide valuable content. Thank you!
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. RCTRootView is a UIView that holds a React Native app. It also provides an interface between native side and the hosted app.
RCTRootView has an initializer that allows you to pass arbitrary properties down to the React Native app. The initialProperties parameter has to be an instance of NSDictionary. The dictionary is internally converted into a JSON object that the top-level JS component can reference.
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. RCTRootView is a UIView that holds a React Native app. It also provides an interface between native side and the hosted app.
RCTRootView has an initializer that allows you to pass arbitrary properties down to the React Native app. The initialProperties parameter has to be an instance of NSDictionary. The dictionary is internally converted into a JSON object that the top-level JS component can reference.
DatePickerAndroid # | Edit on GitHub |
Opens the standard Android date picker dialog.
Example #
DatePickerAndroid # | Edit on GitHub |
Opens the standard Android date picker dialog.
Example #
day if the user picked a date. If the user dismissed the dialog, the Promise will
still be resolved with action being DatePickerAndroid.dismissedAction and all the other keys
being undefined. Always check whether the action before reading the values.Note the native date picker dialog has some UI glitches on Android 4 and lower
-when using the minDate and maxDate options.
static dateSetAction() #
A date has been selected.
static dismissedAction() #
The dialog has been dismissed.
Examples # | Edit on GitHub |
minDate and maxDate options.static dateSetAction() #
A date has been selected.
static dismissedAction() #
The dialog has been dismissed.
Examples # | Edit on GitHub |
DatePickerIOS # | Edit on GitHub |
Use DatePickerIOS to render a date/time picker (selector) on iOS. This is
+
DatePickerIOS # | Edit on GitHub |
Use DatePickerIOS to render a date/time picker (selector) on iOS. This is
a controlled component, so you must hook in to the onDateChange callback
and update the date prop in order for the component to update, otherwise
the user's change will be reverted immediately to reflect props.date as the
@@ -6,7 +6,7 @@ source of truth.
Props
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.
Examples # | Edit on GitHub |
Examples # | Edit on GitHub |
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
⌘ + morF2to 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.
Android logging #
Run adb logcat *:S ReactNative:V ReactNativeJS:V in a terminal to see your Android app's logs.
Reload #
Selecting Reload (or pressing ⌘ + r in the iOS simulator) will reload the JavaScript that powers your application. If you have added new resources (such as an image to Images.xcassets on iOS or to res/drawable folder 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.
YellowBox/RedBox #
Using console.warn will display an on-screen log on a yellow background. Click on this warning to show more information about it full screen and/or dismiss the warning.
You can use console.error to display a full screen error on a red background.
By default, the warning box is enabled in __DEV__. Set the following flag to disable it:
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
⌘ + morF2to 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.
Android logging #
Run adb logcat *:S ReactNative:V ReactNativeJS:V in a terminal to see your Android app's logs.
Reload #
Selecting Reload (or pressing ⌘ + r in the iOS simulator) will reload the JavaScript that powers your application. If you have added new resources (such as an image to Images.xcassets on iOS or to res/drawable folder 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.
YellowBox/RedBox #
Using console.warn will display an on-screen log on a yellow background. Click on this warning to show more information about it full screen and/or dismiss the warning.
You can use console.error to display a full screen error on a red background.
By default, the warning box is enabled in __DEV__. Set the following flag to disable it:
Specific warnings can be ignored programmatically by setting the array:
Strings in console.ignoredYellowBox can be a prefix of the warning that should be ignored.
Chrome Developer Tools #
To debug the JavaScript code in Chrome, select Debug JS Remotely from the developer menu. This will open a new tab at http://localhost:8081/debugger-ui.
In Chrome, press ⌘ + option + i or select View → Developer → Developer Tools to 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.
Custom JavaScript debugger #
To use a custom JavaScript debugger define the REACT_DEBUGGER environment variable to a command that will start your custom debugger. That variable will be read from the Packager process. If that environment variable is set, selecting Debug JS Remotely from the developer menu will execute that command instead of opening Chrome. The exact command to be executed is the contents of the REACT_DEBUGGER environment variable followed by the space separated paths of all project roots (e.g. If you set REACT_DEBUGGER="node /path/to/launchDebugger.js --port 2345 --type ReactNative" then the command "node /path/to/launchDebugger.js --port 2345 --type ReactNative /path/to/reactNative/app" will end up being executed). Custom debugger commands executed this way should be short-lived processes, and they shouldn't produce more than 200 kilobytes of output.
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-rc and higher versions, you can enable a FPS graph overlay in the developers menu in order to help you debug performance problems.
We are planning improvements to the React Native documentation. Your responses to this short survey will go a long way in helping us provide valuable content. Thank you!
Dimensions # | Edit on GitHub |
Methods #
static set(dims) #
This should only be called from native code by sending the +
Dimensions # | Edit on GitHub |
Methods #
static set(dims) #
This should only be called from native code by sending the didUpdateDimensions event.
@param {object} dims Simple string-keyed object of dimensions to set
static get(dim) #
Initial dimensions are set before runApplication is 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
@@ -21,6 +21,6 @@ setting a value in a StyleSheet).
Example: It is sometimes necessary to make changes directly to a component
+ 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
@@ -146,6 +146,6 @@ use React component that wraps the platform React component that wraps the platform Since React makes no assumptions about the rest of your technology stack, it's easily embeddable within an existing non-React Native app. In your app's In your project's Since React makes no assumptions about the rest of your technology stack, it's easily embeddable within an existing non-React Native app. In your app's In your project's Since React makes no assumptions about the rest of your technology stack – it’s commonly noted as simply the At this point you should have the React Native package installed under a directory named 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 Since React makes no assumptions about the rest of your technology stack – it’s commonly noted as simply the At this point you should have the React Native package installed under a directory named 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 The Geolocation API follows the web spec:
+ The Geolocation API follows the web spec:
https://developer.mozilla.org/en-US/docs/Web/API/Geolocation You need to include the To request access to location, you need to add the following line to your
@@ -6,7 +6,7 @@ app's Invokes the success callback whenever the location changes. Supported
-options: timeout (ms), maximumAge (ms), enableHighAccuracy (bool), distanceFilter(m) 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 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: These features make users more comfortable while using an app, because it allows people to experiment and interact without fear of making mistakes. The responder system can be complicated to use. So we have provided an abstract 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: If the View returns true and attempts to become the responder, one of the following will happen: If the view is responding, the following handlers can be called: 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 For higher-level gesture interpretation, check out PanResponder. We are planning improvements to the React Native documentation. Your responses to this short survey will go a long way in helping us provide valuable content. Thank you! 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 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: These features make users more comfortable while using an app, because it allows people to experiment and interact without fear of making mistakes. The responder system can be complicated to use. So we have provided an abstract 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: If the View returns true and attempts to become the responder, one of the following will happen: If the view is responding, the following handlers can be called: 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 For higher-level gesture interpretation, check out PanResponder. We are planning improvements to the React Native documentation. Your responses to this short survey will go a long way in helping us provide valuable content. Thank you! The React Native command line tools allow you to easily create and initialize projects, etc. If you see the error, Xcode 7.0 or higher. Open the App Store or go to https://developer.apple.com/xcode/downloads/. This will also install Xcode 7.0 or higher is required. You can install Xcode via the App Store or Apple developer downloads. This will install the Xcode IDE and Xcode Command Line Tools. While generally installed by default, you can verify that the Xcode Command Line Tools are installed by launching Xcode and selecting Android Studio 2.0 or higher. Android Studio requires the Java Development Kit [JDK] 1.8 or higher. You can type
Get started with Nuclide here. Genymotion is an alternative to the stock Google emulator that comes with Android Studio.
-However, it's only free for personal use. If you want to use the stock Google emulator, see below. There is a known bug on some versions
+However, it's only free for personal use. If you want to use Genymotion, see below. There is a known bug on some versions
of Android Studio where a virtual device will not be created, even though you selected it in the
installation sequence. You may see this at the end of the installation: If you see this, run Then select the new device in the AVD Manager window and click If you encounter: A React component for displaying different types of images,
+ 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: 'contain': Scale the image uniformly (maintain the image's aspect ratio)
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. Changes the color of all the non-transparent pixels to the tintColor. When the image has rounded corners, specifying an overlayColor will
+aspect ratio of the src. The image source (either a remote URL or a local file resource). Changes the color of all the non-transparent pixels to the tintColor. 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:
@@ -36,14 +34,14 @@ the image. A static image to display while loading the image source. Invoked on load error with Invoked on download progress with Retrieve the width and height (in pixels) of an image prior to displaying it.
+Apple documentation A static image to display while loading the image source. Invoked on load error with Invoked on download progress with Retrieve the width and height (in pixels) of an image prior to displaying it.
This method can fail if the image cannot be found, or fails to download. In order to retrieve the image dimensions, the image may first need to be
loaded or downloaded, after which it will be cached. This means that in
principle you could use this method to preload images, however it is not
optimized for that purpose, and may in future be implemented in a way that
does not fully load/download the image data. A proper, supported way to
preload images will be provided as a separate API. Prefetches a remote image for later use by downloading it to the disk
-cache 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: The image name is resolved the same way JS modules are resolved. In the example above the packager will look for You can also use 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: The image name is resolved the same way JS modules are resolved. In the example above the packager will look for You can also use See CameraRoll for an example of
-using local resources that are outside of iOS saves multiple sizes for the same image in your Camera Roll, it is very important to pick the one that's as close as possible for performance reasons. You wouldn't want to use the full quality 3264x2448 image as source when displaying a 200x200 thumbnail. If there's an exact match, React Native will pick it, otherwise it's going to use the first one that's at least 50% bigger in order to avoid blur when resizing from a close size. All of this is done by default so you don't have to worry about writing the tedious (and error prone) code to do it yourself. In the browser if you don't give a size to an image, the browser is going to render a 0x0 element, download the image, and then render the image based with the correct size. The big issue with this behavior is that your UI is going to jump all around as images load, this makes for a very bad user experience. In React Native this behavior is intentionally not implemented. It is more work for the developer to know the dimensions (or aspect ratio) of the remote image in advance, but we believe that it leads to a better user experience. Static images loaded from the app bundle via the For example, the result of In React Native, one interesting decision is that the On the infrastructure side, the reason is that it allows us to attach metadata to this object. For example if you are using On the user side, this lets you annotate the object with useful attributes such as the dimension of the image in order to compute the size it's going to be displayed in. Feel free to use it as your data structure to store more information about your image. A common feature request from developers familiar with the web is iOS saves multiple sizes for the same image in your Camera Roll, it is very important to pick the one that's as close as possible for performance reasons. You wouldn't want to use the full quality 3264x2448 image as source when displaying a 200x200 thumbnail. If there's an exact match, React Native will pick it, otherwise it's going to use the first one that's at least 50% bigger in order to avoid blur when resizing from a close size. All of this is done by default so you don't have to worry about writing the tedious (and error prone) code to do it yourself. In the browser if you don't give a size to an image, the browser is going to render a 0x0 element, download the image, and then render the image based with the correct size. The big issue with this behavior is that your UI is going to jump all around as images load, this makes for a very bad user experience. In React Native this behavior is intentionally not implemented. It is more work for the developer to know the dimensions (or aspect ratio) of the remote image in advance, but we believe that it leads to a better user experience. Static images loaded from the app bundle via the For example, the result of In React Native, one interesting decision is that the On the infrastructure side, the reason is that it allows us to attach metadata to this object. For example if you are using On the user side, this lets you annotate the object with useful attributes such as the dimension of the image in order to compute the size it's going to be displayed in. Feel free to use it as your data structure to store more information about your image. A common feature request from developers familiar with the web is NOTE: If your app was launched from an external url registered to your app you can
+ NOTE: 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 Refer
apiKey: '2c98749b4a1e588efec53b2acec13025',
indexName: 'react-native-versions',
inputSelector: '#algolia-doc-search',
- algoliaOptions: { facetFilters: [ "tags:0.27" ], hitsPerPage: 5 }
+ algoliaOptions: { facetFilters: [ "tags:0.28" ], hitsPerPage: 5 }
});
\ No newline at end of file
diff --git a/docs/interactionmanager.html b/docs/interactionmanager.html
index 8bce6da1932..e689c8b04de 100644
--- a/docs/interactionmanager.html
+++ b/docs/interactionmanager.html
@@ -1,4 +1,4 @@
-var {height,
apiKey: '2c98749b4a1e588efec53b2acec13025',
indexName: 'react-native-versions',
inputSelector: '#algolia-doc-search',
- algoliaOptions: { facetFilters: [ "tags:0.27" ], hitsPerPage: 5 }
+ algoliaOptions: { facetFilters: [ "tags:0.28" ], hitsPerPage: 5 }
});
\ No newline at end of file
diff --git a/docs/direct-manipulation.html b/docs/direct-manipulation.html
index 32c99c52ea4..66104847337 100644
--- a/docs/direct-manipulation.html
+++ b/docs/direct-manipulation.html
@@ -1,4 +1,4 @@
-Direct Manipulation #
Edit on GitHub Direct Manipulation #
Edit on GitHub setState instead of setNativeProps.DrawerLayoutAndroid #
Edit on GitHub DrawerLayout (Android only). The
+DrawerLayoutAndroid #
Edit on GitHub DrawerLayout (Android only). The
Drawer (typically used for navigation) is rendered with renderNavigationView
and 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
@@ -53,6 +53,6 @@ effect on API 21+.
\ No newline at end of file
diff --git a/docs/embedded-app-android.html b/docs/embedded-app-android.html
index 46e007c569d..501a8630462 100644
--- a/docs/embedded-app-android.html
+++ b/docs/embedded-app-android.html
@@ -1,9 +1,9 @@
-
Integrating with Existing Apps #
Edit on GitHub Requirements #
Prepare your app #
build.gradle file add the React Native dependency:build.gradle file add an entry for the local React Native maven directory:Integrating with Existing Apps #
Edit on GitHub Requirements #
Prepare your app #
build.gradle file add the React Native dependency:build.gradle file add an entry for the local React Native maven directory:Integrating with Existing Apps #
Edit on GitHub V in MVC – it’s easily embeddable within an existing non-React Native app. In fact, it integrates with other best practice community tools like CocoaPods.Requirements #
gem install cocoapodsnvm 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 typing node. With nvm you can install multiple versions of Node.js and easily switch between them.react-native package from npm by running the following command in the root directory of your project:npm install react-nativenode_modules as a sibling to your .xcodeproj file.Install React Native Using CocoaPods #
Podfile. If you don't have one, then create it under the root directory of your project.Integrating with Existing Apps #
Edit on GitHub V in MVC – it’s easily embeddable within an existing non-React Native app. In fact, it integrates with other best practice community tools like CocoaPods.Requirements #
gem install cocoapodsnvm 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 typing node. With nvm you can install multiple versions of Node.js and easily switch between them.react-native package from npm by running the following command in the root directory of your project:npm install react-nativenode_modules as a sibling to your .xcodeproj file.Install React Native Using CocoaPods #
Podfile. If you don't have one, then create it under the root directory of your project.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 #
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 #
Edit on GitHub Geolocation #
Edit on GitHub iOS #
NSLocationWhenInUseUsageDescription key
in Info.plist to enable geolocation. Geolocation is enabled by default
when you create a project with react-native init.Android #
AndroidManifest.xml:<uses-permission and
options: timeout (ms), maximumAge (ms), enableHighAccuracy (bool)
On Android, this can return almost immediately if the location is cached or
request an update, which might take a while.static watchPosition(success, error?, options?) #
static clearWatch(watchID) #
static stopObserving() #
Examples #
Edit on GitHub static clearWatch(watchID) #
static stopObserving() #
Examples #
Edit on GitHub Gesture Responder System #
Edit on GitHub ResponderEventPlugin.js, which contains further details and documentation.Best Practices #
TouchableHighlight and Touchable* #
Touchable implementation for things that should be "tappable". This uses the responder system and allows you to easily configure tap interactions declaratively. Use TouchableHighlight anywhere where you would use a button or link on web.Responder Lifecycle #
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?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 itView.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 to onResponderTerminationRequest, or might be taken by the OS without asking (happens with control center/ notification center on iOS)evt is 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 screenCapture ShouldSet Handlers #
onStartShouldSetResponder and onMoveShouldSetResponder are 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 *ShouldSetResponder handlers. This is desirable in most cases, because it makes sure all controls and buttons are usable.on*ShouldSetResponderCapture. So if a parent View wants to prevent the child from becoming responder on a touch start, it should have a onStartShouldSetResponderCapture handler which returns true.View.props.onStartShouldSetResponderCapture: (evt) => true,View.props.onMoveShouldSetResponderCapture: (evt) => true,PanResponder #
Gesture Responder System #
Edit on GitHub ResponderEventPlugin.js, which contains further details and documentation.Best Practices #
TouchableHighlight and Touchable* #
Touchable implementation for things that should be "tappable". This uses the responder system and allows you to easily configure tap interactions declaratively. Use TouchableHighlight anywhere where you would use a button or link on web.Responder Lifecycle #
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?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 itView.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 to onResponderTerminationRequest, or might be taken by the OS without asking (happens with control center/ notification center on iOS)evt is 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 screenCapture ShouldSet Handlers #
onStartShouldSetResponder and onMoveShouldSetResponder are 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 *ShouldSetResponder handlers. This is desirable in most cases, because it makes sure all controls and buttons are usable.on*ShouldSetResponderCapture. So if a parent View wants to prevent the child from becoming responder on a touch start, it should have a onStartShouldSetResponderCapture handler which returns true.View.props.onStartShouldSetResponderCapture: (evt) => true,View.props.onMoveShouldSetResponderCapture: (evt) => true,PanResponder #
Getting Started #
Edit on GitHub Getting Started #
Edit on GitHub React Native Command Line Tools #
EACCES: permission denied, please run the command:
sudo npm install -g react-native-cli.Xcode #
git as well.Xcode #
Xcode | Preferences | Locations and ensuring there is a version of the command line tools shown in the Command Line Tools list box. The Command Line Tools give you git, etc.Android Studio #
javac -version to see what version you have, if any. If you do not meet the JDK requirement,
@@ -80,7 +80,7 @@ for writing, React Native applications.Genymotion #
Troubleshooting #
Virtual Device Not Created When Installing Android Studio #
Troubleshooting #
Virtual Device Not Created When Installing Android Studio #
android avd and create the virtual device manually.
Start....Shell Command Unresponsive Exception #
Image #
Edit on GitHub Image #
Edit on GitHub source {uri: string}, number #
uri is 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 the require('./path/to/image.png') function).style style #
backfaceVisibility enum('visible', 'hidden')
backgroundColor color
borderBottomLeftRadius number
borderBottomRightRadius number
borderColor color
borderRadius number
borderTopLeftRadius number
borderTopRightRadius number
borderWidth number
opacity number
overflow enum('visible', 'hidden')
resizeMode Object.keys(ImageResizeMode)
tintColor color
androidoverlayColor string
source ImageSourcePropType #
style style #
backfaceVisibility enum('visible', 'hidden')
backgroundColor color
borderBottomLeftRadius number
borderBottomRightRadius number
borderColor color
borderRadius number
borderTopLeftRadius number
borderTopRightRadius number
borderWidth number
opacity number
overflow enum('visible', 'hidden')
resizeMode Object.keys(ImageResizeMode)
tintColor color
androidoverlayColor string
iosdefaultSource {uri: string}, number #
iosonError function #
{nativeEvent: {error}}iosonProgress function #
{nativeEvent: {loaded, total}}Methods #
static getSize(uri: string, success: (width: number, height: number) => void, failure: (error: any) => void) #
iosdefaultSource {uri: string, width: number, height: number, scale: number}, number #
iosonError function #
{nativeEvent: {error}}iosonProgress function #
{nativeEvent: {loaded, total}}Methods #
static getSize(uri: string, success: (width: number, height: number) => void, failure: (error: any) => void) #
static prefetch(url: string) #
Examples #
Edit on GitHub Examples #
Edit on GitHub Images #
Edit on GitHub Static Image Resources #
my-icon.png in the same folder as the component that requires it. Also if you have my-icon.ios.png and my-icon.android.png, the packager will pick the file depending on the platform you are running on.@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 #
Edit on GitHub Static Image Resources #
my-icon.png in the same folder as the component that requires it. Also if you have my-icon.ios.png and my-icon.android.png, the packager will pick the file depending on the platform you are running on.@2x, @3x, etc. suffix in the file name to provide images for different screen densities. For example, if you have the following file structure:Local Filesystem Images #
Images.xcassets.Best Camera Roll Image #
Why Not Automatically Size Everything? #
require('./my-icon.png') syntax can be automatically sized because their dimensions are available immediately at the time of mounting.require('./my-icon.png') might be:Source as an object #
src attribute is named source and doesn't take a string but an object with an uri attribute.require('./my-icon.png'), then we add information about its actual location and size (don't rely on this fact, it might change in the future!). This is also future proofing, for example we may want to support sprites at some point, instead of outputting {uri: ...}, we can output {uri: ..., crop: {left: 10, top: 50, width: 20, height: 40}} and transparently support spriting on all the existing call sites.Background Image via Nesting #
background-image. To handle this use case, simply create a normal <Image> component and add whatever children to it you would like to layer on top of it.Images.xcassets.Best Camera Roll Image #
Why Not Automatically Size Everything? #
require('./my-icon.png') syntax can be automatically sized because their dimensions are available immediately at the time of mounting.require('./my-icon.png') might be:Source as an object #
src attribute is named source and doesn't take a string but an object with a uri attribute.require('./my-icon.png'), then we add information about its actual location and size (don't rely on this fact, it might change in the future!). This is also future proofing, for example we may want to support sprites at some point, instead of outputting {uri: ...}, we can output {uri: ..., crop: {left: 10, top: 50, width: 20, height: 40}} and transparently support spriting on all the existing call sites.Background Image via Nesting #
background-image. To handle this use case, simply create a normal <Image> component and add whatever children to it you would like to layer on top of it.Images.xcassets.<
apiKey: '2c98749b4a1e588efec53b2acec13025',
indexName: 'react-native-versions',
inputSelector: '#algolia-doc-search',
- algoliaOptions: { facetFilters: [ "tags:0.27" ], hitsPerPage: 5 }
+ algoliaOptions: { facetFilters: [ "tags:0.28" ], hitsPerPage: 5 }
});
\ No newline at end of file
diff --git a/docs/intentandroid.html b/docs/intentandroid.html
index 4d6a04ab2c7..132108caeff 100644
--- a/docs/intentandroid.html
+++ b/docs/intentandroid.html
@@ -1,4 +1,4 @@
-
IntentAndroid #
Edit on GitHub IntentAndroid is being deprecated. Use Linking instead.IntentAndroid gives you a general interface to handle external links.Basic Usage #
Handling deep links #
IntentAndroid #
Edit on GitHub IntentAndroid is being deprecated. Use Linking instead.IntentAndroid gives you a general interface to handle external links.Basic Usage #
Handling deep links #
null