WebViewJavascriptBridge－Obj-C和JavaScript互通消息的桥梁
译者：@coderyi9
本文翻译自Marcus Westin的开源框架WebViewJavascriptBridge的readme,英文原文链接https://github.com/marcuswestin/WebViewJavascriptBridge.
WebViewJavascriptBridge是Obj-C和JavaScript通过UIWebViews/WebViews互通消息的一个iOS/OSX的桥梁. 如果你喜欢WebViewJavascriptBridge,你可能也想check outWebViewProxy.
Obj-C和JavaScript原理简单说一下，Obj-C调用JavaScript很简单，可以通过webview的stringByEvaluatingJavaScriptFromString:方法调用JavaScript代码；JavaScript调用Obj-C，则是通过web view的代理方法shouldStartLoadWithRequest：来接收JavaScript的网络请求从而实现调用。
正在使用WebViewJavascriptBridge的项目
有很多的公司和项目在使用WebViewJavascriptBridge.这个列表不完整,你可以随意添加.
-
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
安装& 例子 (iOS & OSX)
首先打开Example Apps文件夹.打开iOS或者OSX的工程然后点击运行.
在你自己的工程中用WebViewJavascriptBridge:
1) 拖动 WebViewJavascriptBridge 文件夹到你的工程中.
在出现的对话框中, 取消 (我觉得应该是选中)”Copy items into destination group’s folder” 并且 选择 “Create groups for any folders”
2) 引入头文件并且申明一个属性:
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#import "WebViewJavascriptBridge.h"
...
@property WebViewJavascriptBridge* bridge;
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3) 实例化WebViewJavascriptBridge并且带上一个UIWebView (iOS)或者WebView (OSX):
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self.bridge = [WebViewJavascriptBridge bridgeForWebView:webView handler:^(id data, WVJBResponseCallback responseCallback) {
NSLog(@
"Received message from javascript: %@"
, data);
responseCallback(@
"Right back atcha"
);
}];
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4) 首先从ObjC到javascript发送一些消息:
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[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);
}];
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5) 然后,看看javascript这边:
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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)
})
})
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Contributors & Forks
Contributors: https://github.com/marcuswestin/WebViewJavascriptBridge/graphs/contributors
Forks: https://github.com/marcuswestin/WebViewJavascriptBridge/network/members
API 参考
ObjC API
[WebViewJavascriptBridge bridgeForWebView: (UIWebView/WebView*)webview handler:(WVJBHandler)handler]
[WebViewJavascriptBridge bridgeForWebView:
(UIWebView/WebView*)webview webViewDelegate:
(UIWebViewDelegate*)webViewDelegate handler:(WVJBHandler)handler]
给web view创建一个javascript的桥梁.
假如javascript需要一个反馈,那么 WVJBResponseCallback 不能为 nil .
当然,通过 webViewDelegate:(UIWebViewDelegate*)webViewDelegate 你可以得到web view的生命周期事件.
例子:
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[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) {
/* ... */
}];
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[bridge send:(id)data]
[bridge send:(id)data responseCallback:(WVJBResponseCallback)responseCallback]
发送一个消息给javascript. 并且在发送消息成功后可以通过 responseCallback block做出一 些反应.
例子:
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[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);
}];
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[bridge registerHandler:(NSString*)handlerName handler: (WVJBHandler)handler]
注册一个叫做 handlerName 的handler. javascript能够通过 WebViewJavascriptBridge.callHandler(“handlerName”) 调起这个handler.
例子:
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[self.bridge registerHandler:@
"getScreenHeight"
handler:^(id data, WVJBResponseCallback responseCallback) {
responseCallback([NSNumber numberWithInt:[UIScreen mainScreen].bounds.size.height]);
}];
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[bridge callHandler:(NSString*)handlerName data:(id)data]
[bridge callHandler:(NSString*)handlerName data:(id)data responseCallback:(WVJBResponseCallback)callback]
调起javascript叫做 handlerName的handler. 在调用 handler成功后可以通过responseCallback block做出反应.
例子:
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[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);
}];
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定义 bundle
WebViewJavascriptBridge 要求 WebViewJavascriptBridge.js.txt 文件嵌入到web view来创建一个在JS这边的桥梁.标准的实现是用 mainBundle 找到这个文件.如果你建立一个 静态库并且你把这个文件放在其他地方,你可以用下面的方法找 WebViewJavascriptBridge.js.txt 文件:
[WebViewJavascriptBridge bridgeForWebView:
(UIWebView/WebView*)webView webViewDelegate:
(UIWebViewDelegate*)webViewDelegate handler:(WVJBHandler)handler
resourceBundle:(NSBundle*)bundle
例子:
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[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"
]]
];
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Javascript API
document.addEventListener(‘WebViewJavascriptBridgeReady’,
function onBridgeReady(event) { … }, false)
一直等待 WebViewJavascriptBridgeReady DOM 事件.
例子:
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document.addEventListener(
'WebViewJavascriptBridgeReady'
,
function
(event) {
var
bridge = event.bridge
// Start using the bridge
},
false
)
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bridge.init(function messageHandler(data, response) { … })
初始化这个桥. 这会调起 ‘WebViewJavascriptBridgeReady’ 的事件handler.
这个 messageHandler 函数会接收通过ObjC的 [bridge send:(id)data] 和 [bridge send:(id)data responseCallback:(WVJBResponseCallback)responseCallback] 方法 发送的所有消息.
如果ObjC发送消息时有WVJBResponseCallback block,那么可以通过response对象发送消息.
例子:
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bridge.init(
function
(data, responseCallback) {
alert(
"Got data "
+ JSON.stringify(data))
if
(responseCallback) {
responseCallback(
"Right back atcha!"
)
}
})
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bridge.send(“Hi there!”)
bridge.send({ Foo:”Bar” })
bridge.send(data, function responseCallback(responseData) { …
})
给ObjC发送消息. 在发送成功后可以通过 responseCallback 函数做出反应.
例子:
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bridge.send(
"Hi there!"
)
bridge.send(
"Hi there!"
,
function
(responseData) {
alert(
"I got a response! "
+JSON.stringify(responseData))
})
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bridge.registerHandler(“handlerName”, function(responseData) { … })
注册一个叫做 handlerName 的handler. ObjC能够通过 [bridge callHandler:”handlerName” data:@”Foo”] 和 [bridge callHandler:”handlerName” data:@”Foo” responseCallback:^(id responseData) { … }] 两个方法调起这个handler.
例子:
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bridge.registerHandler(
"showAlert"
,
function
(data) { alert(data) })
bridge.registerHandler(
"getCurrentPageUrl"
,
function
(data, responseCallback) {
responseCallback(document.location.toString())
})
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iOS4 支持 (包括 JSONKit)
注:iOS4支持尚未在V2 +测试.
WebViewJavascriptBridge 默认使用 NSJSONSerialization .如果你需要iOS 4的支持,你可以用JSONKit,并且增加 USE_JSONKIT 的预处理宏到你的工程中.