A standalone iOS class for sending messages to and from javascript in a UIWebView
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ExampleApp.xcodeproj
ExampleApp
WebViewJavascriptBridge
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README.md

README.md

WebViewJavascriptBridge

An iOS bridge for sending messages to and from javascript in a UIWebView.

If you like WebViewJavascriptBridge you should also check out WebViewProxy.

In the Wild

WebViewJavascriptBridge is used by a range of companies and projects. This list was just started and is still very incomplete.

Are you using WebViewJavascript at your company? Add it and send us a pull request!

Setup & Examples

Just open the Xcode project and hit run to see ExampleApp run.

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"
  1. Import the header file:

    #import "WebViewJavascriptBridge.h"

  2. Instantiate a UIWebView and a WebViewJavascriptBridge:

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

  3. 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:

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

API Reference

ObjC API

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

Create a javascript bridge for the given UIWebView.

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 UIWebView'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.

Contributors