Web View Javascript Bridge

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

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:

#import "WebViewJavascriptBridge.h"

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

WebViewJavascriptBridge* 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:

[bridge send:@"Well hello there"];
[bridge send:[NSDictionary dictionaryWithObject:@"Foo" forKey:@"Bar"]];
[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)
    })
})

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:

[bridge send:@"Hi"];
[bridge send:[NSDictionary dictionaryWithObject:@"Foo" forKey:@"Bar"]];
[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:

[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:

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

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.

Download: https://github.com/marcuswestin/WebViewJavascriptBridge/archive/master.zip