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

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README.md

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.

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);
}];

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.

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