WKWebView Component for React Native

React Native comes with WebView component, which uses UIWebView on iOS. This component uses WKWebView introduced in iOS 8 with all the performance boost. Deployment Target >= iOS 8.0 is required

Install

Alternative #1

1. Install from npm (note the postfix in the package name): npm install react-native-wkwebview-reborn
2. In the XCode's "Project navigator", right click on your project's Libraries folder ➜ Add Files to <...>
3. Go to node_modules ➜ react-native-wkwebview ➜ ios ➜ select RCTWKWebView folder and create a group
4. Compile and profit (Remember to set Minimum Deployment Target = 8.0)

Alternative #2

1. Install from npm (note the postfix in the package name): npm install react-native-wkwebview-reborn
2. run rnpm link

Notes to iOS 8:

If you install from using Alterntive #2, you might encounter bugs in iOS 8.2 (We've only tested this version) where the app crashes with dyld_fatal_error. This can be solved using Alternative #1. We were still unable to find the cause of the first bug so I recommend that you link the library using Alternative #1.

Usage

import WKWebView from 'react-native-wkwebview-reborn';

Try replacing your existing WebView with WKWebView and it should work in most cases.

Note on version

React Native 0.40 breaks library compatibility, so we currently have two branches:

• 0.X.X: for RN < 0.40
• 1.X.X: for RN >= 0.40

Please choose accordingly. We will try to make sure both branches have the same set of features until most people have upraded to 0.40

Compatibility with UIWebView

WKWebView aims to be a drop-in replacement for UIWebView. However, some legacy UIWebView properties are not supported.

Additional props:

• onProgress

A callback to get the loading progress of WKWebView. Derived from estimatedProgress property.

<WKWebView onProgress={(progress) => console.log(progress)} />

progress is a double between 0 and 1.

• openNewWindowInWebView (New in 0.4.0)

If set to true, links with target="_blank" or window.open will be opened in the current webview, not in Safari. Default is false.

• sendCookies

Set sendCookies to true to copy cookies from sharedHTTPCookieStorage when calling loadRequest. This emulates the behavior of react-native's WebView component.

• source={{file: '', allowingReadAccessToURL: '' }}

This allows WKWebView loads a local HTML file. Please note the underlying API is only introduced in iOS 9+. So in iOS 8, it will simple ignores these two properties. It allows you to provide a fallback URL for iOS 8 users.

<WKWebView source={{ file: RNFS.MainBundlePath + '/data/index.html', allowingReadAccessToURL: RNFS.MainBundlePath }} />

From WKWebview -> React Native (New in 0.3.0)

• onMessage

This utilizes the message handlers in WKWebView and allows you to post message from webview to React Native. For example:

<WKWebView onMessage={(e) => console.log(e)} />

Then in your webview, you can post message to React Native using

window.webkit.messageHandlers.reactNative.postMessage({data: 'hello!'});

Then your React Native should have

{name: 'reactNative', body: {data: 'hello!'}}

The data serialization flow is as follows:

JS --- (via WKWebView) --> ObjC --- (via React Native Bridge) ---> JS

So I recommend to keep your data simple and JSON-friendly.

From React Native -> WkWebView (New in 0.3.0)

There is a evaluateJavaScript method on WKWebView, which does exactly what its name suggests. To send message from React Native to WebView, you can define a callback method on your WebView:

window.receivedMessageFromReactNative = function(data) {
  // Code here
  console.log(data);
}

Then you can send message from React Native with this method call:

// <WKWebView ref="webview" />
this.refs.webview.evaluateJavaScript('receivedMessageFromReactNative("Hello from the other side.")');

Currently supported props are:

• automaticallyAdjustContentInsets
• contentInset
• html (deprecated)
• injectedJavaScript
• onError
• onLoad
• onLoadEnd
• onLoadStart
• onNavigationStateChange
• renderError
• renderLoading
• source
• startInLoadingState
• style
• url (deprecated)
• bounces
• onShouldStartLoadWithRequest
• pagingEnabled
• scrollEnabled

Unsupported props are:

• mediaPlaybackRequiresUserAction
• scalesPageToFit
• domStorageEnabled
• javaScriptEnabled
• allowsInlineMediaPlayback
• decelerationRate

If you look at the source, the JavaScript side is mostly derived from React Native's WebView. The Objective C side mostly deals with the API difference between UIWebView and WKWebView.

Contribute

We battle test this component against our app. However, we haven't use all the props so if something does not work as expected, please open an issue or PR.