iOS和JS互调--WebViewJavascriptBridge使用说明

在App中，会碰到使用webview，嵌入HTML，然手需要与JS互调的需求。
下面来说一下WebViewJavascriptBridge在ios端怎么样使用。
1.Objective-C初始化

UIWebView* webView = [[UIWebView alloc] initWithFrame:self.view.bounds];
    [self.view addSubview:webView];

2.将此webview与WebViewJavascriptBridge关联（viewdidload）

if (_bridge) {
    return; 
}
[WebViewJavascriptBridge enableLogging];
_bridge = [WebViewJavascriptBridge bridgeForWebView:webView webViewDelegate:self handler:^(id data, WVJBResponseCallback responseCallback) {
    NSLog(@"ObjC received message from JS: %@", data);
    responseCallback(@"Response for message from ObjC");
  }];

3.JavaScript 初始化

function connectWebViewJavascriptBridge(callback) {
    if (window.WebViewJavascriptBridge) {
        callback(WebViewJavascriptBridge);
    } else {
        document.addEventListener('WebViewJavascriptBridgeReady', function() {callback(WebViewJavascriptBridge);}, false);
    }
}
connectWebViewJavascriptBridge(function(bridge) {
    bridge.init(function(message, responseCallback) {
            log('JS got a message', message)
            var data = { 'Javascript Responds':'Wee!' }
            log('JS responding with', data)
            responseCallback(data)
    })
});

这里初始化先是创建了一个connectWebViewJavascriptBridge方法，该方法注册了一个WebViewJavascriptBridgeReady事件，同时声明了一个全局的WebViewJavascriptBridge变量。我们可以在外部通过WebViewJavascriptBridge调用相关方法。

在init里面同样有一个function，这个function同样是用来接收Objective-C里面通过send方法发送的消息的，参数与OC里的send方法参数对应

4.Objective-C调用JavaScript
首先要在JavaScript里面注册一个方法：

bridge.registerHandler('showChat', function(data, responseCallback) {
    log('ObjC called showChat with', data)
    var responseData = { 'Javascript Says':'Right back atcha!' }
    log('JS responding with', responseData)
    responseCallback(responseData)
})

OC调用这个方法

[_bridge callHandler:@"showChat" data:data responseCallback:^(id response) {
        NSLog(@"showChat responded: %@", response);
 }];

5.JavaScript调用Objective-C
OC注册一个方法：

[_bridge registerHandler:@"showChat" handler:^(id data, WVJBResponseCallback responseCallback) {
        NSLog(@"showChat called: %@", data);
        responseCallback(@"Response from showChat");
 }];

JavaScript调用方法

bridge.callHandler('showChat', {'foo': 'bar'}, function(response) {
    log('JS got response', response)
});

6.JavaScript向OC中发送消息

bridge.send(data, function(responseData) {
    log('JS got response', responseData)
});

这种方式发送消息实际上是调用了OC初始化时的handle

7.OC向JavaScript发送消息

[_bridge send:@"A string sent from ObjC before Webview has loaded." responseCallback:^(id responseData) {
        NSLog(@"objc got response! %@", responseData);
}];

这个send方法，实际上是调用了JavaScript初始化init里面的function

附上我们应用中app.js的完整代码

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")
        }
    })
    // 向oc发消息
    bridge.send('Hello from the javascript')
    bridge.send('response to xxx', function responseCallback(responseData) {
        console.log("Javascript got its response", responseData)
    })
    // js调用oc方法
    var callbackButton = document.getElementById('callbackButton');
    callbackButton.onclick = function(e) {
        e.preventDefault()
        bridge.callHandler('showChat', {qdId:'100005'}, function(response) {
            console.log('JS got response', response)
        })
    }
    // oc调用js方法
    bridge.registerHandler('callJS', function(data, responseCallback) {
        var responseData = { 'Javascript Says':'Right back atcha!' }
        console.log('JS responding with', responseData)
        responseCallback(responseData)
    })
})

参考：
https://github.com/marcuswestin/WebViewJavascriptBridge