WebViewJavascriptBridge

An iOS/OSX bridge for sending messages between Obj-C and JavaScript in UIWebViews/WebViews.

If you like WebViewJavascriptBridge you may also want to check out WebViewProxy.

In the Wild

WebViewJavascriptBridge is used by a range of companies and projects. This list is incomplete, but feel free to add your's and send a PR.

• Facebook Messenger
• Facebook Paper
• Yardsale
• EverTrue
• Game Insight
• Altralogica
• Sush.io
• Flutterby Labs
• JD Media's 鼎盛中华
• Dojo4's Imbed
• CareZone
• Hemlig
• FRIL

Setup & Examples (iOS & OSX)

Start with the Example Apps/ folder. Open either the iOS or OSX project and hit run to see it in action.

To use a WebViewJavascriptBridge in your own project:

1. Drag the WebViewJavascriptBridge folder into your project.

• In the dialog that appears, uncheck "Copy items into destination group's folder" and select "Create groups for any folders"

2. Import the header file and declare an ivar property:

#import "WebViewJavascriptBridge.h"

...

@property WebViewJavascriptBridge* bridge;

3. Instantiate WebViewJavascriptBridge with a UIWebView (iOS) or WebView (OSX):

self.bridge = [WebViewJavascriptBridge bridgeForWebView:webView handler:^(id data, WVJBResponseCallback responseCallback) {
	NSLog(@"Received message from javascript: %@", data);
	responseCallback(@"Right back atcha");
}];

4. Go ahead and send some messages from ObjC to javascript:

[self.bridge send:@"Well hello there"];
[self.bridge send:[NSDictionary dictionaryWithObject:@"Foo" forKey:@"Bar"]];
[self.bridge send:@"Give me a response, will you?" responseCallback:^(id responseData) {
	NSLog(@"ObjC got its response! %@", responseData);
}];

4. Finally, set up the javascript side:

function connectWebViewJavascriptBridge(callback) {
	if (window.WebViewJavascriptBridge) {
		callback(WebViewJavascriptBridge)
	} else {
		document.addEventListener('WebViewJavascriptBridgeReady', function() {
			callback(WebViewJavascriptBridge)
		}, false)
	}
}

connectWebViewJavascriptBridge(function(bridge) {
	
	/* Init your app here */

	bridge.init(function(message, responseCallback) {
		alert('Received message: ' + message)   
		if (responseCallback) {
			responseCallback("Right back atcha")
		}
	})
	bridge.send('Hello from the javascript')
	bridge.send('Please respond to this', function responseCallback(responseData) {
		console.log("Javascript got its response", responseData)
	})
})

WKWebView Support (iOS 8 & OS 10.10)

WARNING: WKWebView still has many bugs and missing network APIs. It may not be a simple drop-in replacement.

WebViewJavascriptBridge supports WKWebView for iOS 8 and OSX Yosemite. In order to use WKWebView you need to instantiate the WKWebViewJavascriptBridge. The rest of the WKWebViewJavascriptBridge API is the same as WebViewJavascriptBridge.

1. Import the header file:

#import "WKWebViewJavascriptBridge.h"

2. Instantiate WKWebViewJavascriptBridge and with a WKWebView object

WKWebViewJavascriptBridge* bridge = [WKWebViewJavascriptBridge bridgeForWebView:webView handler:^(id data, WVJBResponseCallback responseCallback) {
	NSLog(@"Received message from javascript: %@", data);
	responseCallback(@"Right back atcha");
}];

Contributors & Forks

Contributors: https://github.com/marcuswestin/WebViewJavascriptBridge/graphs/contributors

Forks: https://github.com/marcuswestin/WebViewJavascriptBridge/network/members

API Reference

ObjC API

[WebViewJavascriptBridge bridgeForWebView:(UIWebView/WebView*)webview handler:(WVJBHandler)handler]

[WebViewJavascriptBridge bridgeForWebView:(UIWebView/WebView*)webview webViewDelegate:(UIWebViewDelegate*)webViewDelegate handler:(WVJBHandler)handler]

Create a javascript bridge for the given web view.

The WVJBResponseCallback will not be nil if the javascript expects a response.

Optionally, pass in webViewDelegate:(UIWebViewDelegate*)webViewDelegate if you need to respond to the web view's lifecycle events.

Example:

[WebViewJavascriptBridge bridgeForWebView:webView handler:^(id data, WVJBResponseCallback responseCallback) {
	NSLog(@"Received message from javascript: %@", data);
	if (responseCallback) {
		responseCallback(@"Right back atcha");
	}
}]

[WebViewJavascriptBridge bridgeForWebView:webView webViewDelegate:self handler:^(id data, WVJBResponseCallback responseCallback) { /* ... */ }];

[bridge send:(id)data]

[bridge send:(id)data responseCallback:(WVJBResponseCallback)responseCallback]

Send a message to javascript. Optionally expect a response by giving a responseCallback block.

Example:

[self.bridge send:@"Hi"];
[self.bridge send:[NSDictionary dictionaryWithObject:@"Foo" forKey:@"Bar"]];
[self.bridge send:@"I expect a response!" responseCallback:^(id responseData) {
	NSLog(@"Got response! %@", responseData);
}];

[bridge registerHandler:(NSString*)handlerName handler:(WVJBHandler)handler]

Register a handler called handlerName. The javascript can then call this handler with WebViewJavascriptBridge.callHandler("handlerName").

Example:

[self.bridge registerHandler:@"getScreenHeight" handler:^(id data, WVJBResponseCallback responseCallback) {
	responseCallback([NSNumber numberWithInt:[UIScreen mainScreen].bounds.size.height]);
}];

[bridge callHandler:(NSString*)handlerName data:(id)data]

[bridge callHandler:(NSString*)handlerName data:(id)data responseCallback:(WVJBResponseCallback)callback]

Call the javascript handler called handlerName. Optionally expect a response by giving a responseCallback block.

Example:

[self.bridge callHandler:@"showAlert" data:@"Hi from ObjC to JS!"];
[self.bridge callHandler:@"getCurrentPageUrl" data:nil responseCallback:^(id responseData) {
	NSLog(@"Current UIWebView page URL is: %@", responseData);
}];

Custom bundle

WebViewJavascriptBridge requires WebViewJavascriptBridge.js.txt file that is injected into web view to create a bridge on JS side. Standard implementation uses mainBundle to search for this file. If you e.g. build a static library and you have that file placed somewhere else you can use this method to specify which bundle should be searched for WebViewJavascriptBridge.js.txt file:

[WebViewJavascriptBridge bridgeForWebView:(UIWebView/WebView*)webView webViewDelegate:(UIWebViewDelegate*)webViewDelegate handler:(WVJBHandler)handler resourceBundle:(NSBundle*)bundle

Example:

[WebViewJavascriptBridge bridgeForWebView:_webView
                          webViewDelegate:self
                                  handler:^(id data, WVJBResponseCallback responseCallback) {
                                      NSLog(@"Received message from javascript: %@", data);
                                  }
                           resourceBundle:[NSBundle bundleWithURL:[[NSBundle mainBundle] URLForResource:@"ResourcesBundle" withExtension:@"bundle"]]
];

Javascript API

document.addEventListener('WebViewJavascriptBridgeReady', function onBridgeReady(event) { ... }, false)

Always wait for the WebViewJavascriptBridgeReady DOM event.

Example:

document.addEventListener('WebViewJavascriptBridgeReady', function(event) {
	var bridge = event.bridge
	// Start using the bridge
}, false)

bridge.init(function messageHandler(data, response) { ... })

Initialize the bridge. This should be called inside of the 'WebViewJavascriptBridgeReady' event handler.

The messageHandler function will receive all messages sent from ObjC via [bridge send:(id)data] and [bridge send:(id)data responseCallback:(WVJBResponseCallback)responseCallback].

The response object will be defined if if ObjC sent the message with a WVJBResponseCallback block.

Example:

bridge.init(function(data, responseCallback) {
	alert("Got data " + JSON.stringify(data))
	if (responseCallback) {
		responseCallback("Right back atcha!")
	}
})

bridge.send("Hi there!")

bridge.send({ Foo:"Bar" })

bridge.send(data, function responseCallback(responseData) { ... })

Send a message to ObjC. Optionally expect a response by giving a responseCallback function.

Example:

bridge.send("Hi there!")
bridge.send("Hi there!", function(responseData) {
	alert("I got a response! "+JSON.stringify(responseData))
})

bridge.registerHandler("handlerName", function(responseData) { ... })

Register a handler called handlerName. The ObjC can then call this handler with [bridge callHandler:"handlerName" data:@"Foo"] and [bridge callHandler:"handlerName" data:@"Foo" responseCallback:^(id responseData) { ... }]

Example:

bridge.registerHandler("showAlert", function(data) { alert(data) })
bridge.registerHandler("getCurrentPageUrl", function(data, responseCallback) {
	responseCallback(document.location.toString())
})

iOS4 support (with JSONKit)

Note: iOS4 support has not yet been tested in v2+.

WebViewJavascriptBridge uses NSJSONSerialization by default. If you need iOS 4 support then you can use JSONKit, and add USE_JSONKIT to the preprocessor macros for your project.