diff --git a/docs/accessibility.html b/docs/accessibility.html index d754780fd3d..2f08caeb647 100644 --- a/docs/accessibility.html +++ b/docs/accessibility.html @@ -1,4 +1,4 @@ -
Accessibility # | Edit on GitHub |
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.
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 |
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.
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.
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 |
Display an iOS action sheet. The options object must contain one or more
+
ActionSheetIOS # | Edit on GitHub |
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 in optionsdestructiveButtonIndex (int) - index of destructive button in optionstitle (string) - a title to show above the action sheetmessage (string) - a message to show below the titleDisplay the iOS share sheet. The options object should contain
one or both of:
message (string) - a message to shareurl (string) - a URL to shareNOTE: if url points to a local file, or is a base64-encoded
uri, the file it points to will be loaded and shared directly.
diff --git a/docs/activityindicatorios.html b/docs/activityindicatorios.html
index 1e11c786890..40c65b8b592 100644
--- a/docs/activityindicatorios.html
+++ b/docs/activityindicatorios.html
@@ -1,4 +1,4 @@
-
ActivityIndicatorIOS # | Edit on GitHub |
Whether to show the indicator (true, the default) or hide it (false).
The foreground color of the spinner (default is gray).
Whether the indicator should hide when not animating (true by default).
Invoked on mount and layout changes with
{nativeEvent: { layout: {x, y, width, height}}}.
Size of the indicator. Small has a height of 20, large has a height of 36.
Examples # | Edit on GitHub |
ActivityIndicatorIOS # | Edit on GitHub |
Whether to show the indicator (true, the default) or hide it (false).
The foreground color of the spinner (default is gray).
Whether the indicator should hide when not animating (true by default).
Invoked on mount and layout changes with
{nativeEvent: { layout: {x, y, width, height}}}.
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, diff --git a/docs/alertios.html b/docs/alertios.html index 3ef450e775d..ce7adac88da 100644 --- a/docs/alertios.html +++ b/docs/alertios.html @@ -1,4 +1,4 @@ -
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
diff --git a/docs/android-building-from-source.html b/docs/android-building-from-source.html
index 402ef08afce..2e240f8ba50 100644
--- a/docs/android-building-from-source.html
+++ b/docs/android-building-from-source.html
@@ -1,4 +1,4 @@
-
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.
Assuming you have the Android SDK installed, run android to open the Android SDK Manager.
Make sure you have the following installed:
build.gradle)build.gradle)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.
Assuming you have the Android SDK installed, run android to open the Android SDK Manager.
Make sure you have the following installed:
build.gradle)build.gradle)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:
You can find further instructions on the official page.
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.
Add gradle-download-task as dependency in android/build.gradle:
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)
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.
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:
time is the length of time the trace will be collected in secondssched, gfx, and view are the android SDK tags (collections of markers) we care about: sched gives you information about what's running on each core of your phone, gfx gives you graphics info such as frame boundaries, and view gives 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_name can be found in the AndroidManifest.xml of your app and looks like com.example.appOnce 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.
After opening the trace in your browser (preferably Chrome), you should see something like this:

HINT: Use the WASD keys to strafe and zoom
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.
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.
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:

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:

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:

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:

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.
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
If you identified a native UI problem, there are usually two scenarios:
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:
renderToHardwareTextureAndroid for complex, static content that is being animated/transformed (e.g. the Navigator slide/alpha animations)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.
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.
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)
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.
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:
time is the length of time the trace will be collected in secondssched, gfx, and view are the android SDK tags (collections of markers) we care about: sched gives you information about what's running on each core of your phone, gfx gives you graphics info such as frame boundaries, and view gives 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_name can be found in the AndroidManifest.xml of your app and looks like com.example.appOnce 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.
After opening the trace in your browser (preferably Chrome), you should see something like this:

HINT: Use the WASD keys to strafe and zoom
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.
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.
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:

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:

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:

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:

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.
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
If you identified a native UI problem, there are usually two scenarios:
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:
renderToHardwareTextureAndroid for complex, static content that is being animated/transformed (e.g. the Navigator slide/alpha animations)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.
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.
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 # | 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
diff --git a/docs/animations.html b/docs/animations.html
index 29a73f7741b..1fce0919857 100644
--- a/docs/animations.html
+++ b/docs/animations.html
@@ -1,4 +1,4 @@
-
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
diff --git a/docs/appregistry.html b/docs/appregistry.html
index 7d6f9ef9c07..071cc18d1b1 100644
--- a/docs/appregistry.html
+++ b/docs/appregistry.html
@@ -1,4 +1,4 @@
-
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
diff --git a/docs/appstate.html b/docs/appstate.html
index 010a6029cea..b3f5625c2b3 100644
--- a/docs/appstate.html
+++ b/docs/appstate.html
@@ -1,4 +1,4 @@
-
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.
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
diff --git a/docs/appstateios.html b/docs/appstateios.html
index e0dfbfec03b..969e6fbba75 100644
--- a/docs/appstateios.html
+++ b/docs/appstateios.html
@@ -1,4 +1,4 @@
-AppStateIOS # | Edit on GitHub |
AppStateIOS can tell you if the app is in the foreground or background,
+
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.
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
diff --git a/docs/asyncstorage.html b/docs/asyncstorage.html
index 1c139184a54..c0464ae4e7d 100644
--- a/docs/asyncstorage.html
+++ b/docs/asyncstorage.html
@@ -1,4 +1,4 @@
-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 diff --git a/docs/backandroid.html b/docs/backandroid.html index 92849ae9906..50745d248fd 100644 --- a/docs/backandroid.html +++ b/docs/backandroid.html @@ -1,4 +1,4 @@ -
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.
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:
CameraRoll # | Edit on GitHub |
CameraRoll provides access to the local camera roll / gallery.
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:
Returns a Promise which when resolved will be passed the new URI.
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 |
Clipboard # | Edit on GitHub |
Clipboard gives you an interface for setting and getting content from Clipboard on both iOS and Android
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
Get content of string type, this method returns a Promise, so you can use following code to get clipboard content
Set content of string type. You can use following code to set clipboard content
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:
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:
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.
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 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.
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.
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 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.
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.
DatePickerAndroid # | Edit on GitHub |
Opens the standard Android date picker dialog.
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
diff --git a/docs/debugging.html b/docs/debugging.html
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Debugging # | Edit on GitHub |
To access the in-app developer menu:
control + ⌘ + z in the simulator.⌘ + m or F2 to 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 + R as 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.
Run adb logcat *:S ReactNative:V ReactNativeJS:V in a terminal to see your Android app's logs.
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.
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 |
To access the in-app developer menu:
control + ⌘ + z in the simulator.⌘ + m or F2 to 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 + R as 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.
Run adb logcat *:S ReactNative:V ReactNativeJS:V in a terminal to see your Android app's logs.
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.
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.
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:
RCTWebSocketExecutor.m and change localhost to the IP address of your computer. Shake the device to open the development menu with the option to start debugging.adb command 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 on adb command). Alternatively, you can open dev menu on the device and select Dev Settings, then update Debug server host for device setting to the IP address of your computer.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.
This option allows for your JS changes to trigger automatic reload on the connected device/emulator. To enable this option:
Enable Live Reload via the developer menu to have the application automatically reload when changes are made to the JavaScript.Dev Settings and select Auto reload on JS change optionOn 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.
Dimensions # | Edit on GitHub |
This should only be called from native code by sending the +
Dimensions # | Edit on GitHub |
This should only be called from native code by sending the didUpdateDimensions event.
@param {object} dims Simple string-keyed object of dimensions to set
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 diff --git a/docs/direct-manipulation.html b/docs/direct-manipulation.html index 7dbf90de74e..66faba8d975 100644 --- a/docs/direct-manipulation.html +++ b/docs/direct-manipulation.html @@ -1,4 +1,4 @@ -
Direct Manipulation # | Edit on GitHub |
It is sometimes necessary to make changes directly to a component +
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 a8b0b5b8d58..b6984c80172 100644 --- a/docs/drawerlayoutandroid.html +++ b/docs/drawerlayoutandroid.html @@ -1,4 +1,4 @@ -
DrawerLayoutAndroid # | Edit on GitHub |
React component that wraps the platform DrawerLayout (Android only). The
+
DrawerLayoutAndroid # | Edit on GitHub |
React component that wraps the platform 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
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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.
In your app's build.gradle file add the React Native dependency:
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:
This is only really used in dev mode when reloading JavaScript from the development server, so you can strip this in release builds if you need to.
You need to add some native code in order to start the React Native runtime and get it to render something. To do this, we're going to create an Activity that creates a ReactRootView, starts a React application inside it and sets it as the main content view.