iOS中JavaScript和OC交互
2016-01-14 10:46
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iOS中JavaScript和OC交互
JAN 10TH, 2015在iOS开发中很多时候我们会和UIWebView打交道,目前国内的很多应用都采用了UIWebView的混合编程技术,最常见的是微信公众号的内容页面。前段时间在做微信公众平台相关的开发,发现很多应用场景都是利用HTML5和UIWebView来实现的。
机制
Objective-C语言调用JavaScript语言,是通过UIWebView的 - (NSString *)stringByEvaluatingJavaScriptFromString:(NSString *)script;的方法来实现的。该方法向UIWebView传递一段需要执行的JavaScript代码最后获取执行结果。
JavaScript语言调用Objective-C语言,并没有现成的API,但是有些方法可以达到相应的效果。具体是利用UIWebView的特性:在UIWebView的内发起的所有网络请求,都可以通过delegate函数得到通知。
示例
下面提供一个简单的例子介绍如何相互的调用,实现的效果是在界面上点击一个链接,然后弹出一个对话框判断是否登录成功。(1)示例的HTML的源码如下:
<span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">1</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">2</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">3</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">4</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb 4000 (88, 110, 117) !important;">5</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">6</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">7</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">8</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">9</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">10</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">11</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">12</span> | <html> <head> <meta http-equiv="content-type" content="text/html;charset=utf-8" /> <meta http-equiv="X-UA-Compatible" content="IE=Edge" /> <meta content="always" name="referrer" /> <title>测试网页</title> </head> <body> <br /> <a href="devzeng://login?name=zengjing&password=123456">点击链接</a> </body> </html> |
<span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">1</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">2</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">3</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">4</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">5</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">6</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">7</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">8</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">9</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">10</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">11</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">12</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">13</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">14</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">15</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">16</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">17</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">18</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">19</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">20</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">21</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">22</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">23</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">24</span> | - (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType { NSURL *url = [request URL]; if([[url scheme] isEqualToString:@"devzeng"]) { //处理JavaScript和Objective-C交互 if([[url host] isEqualToString:@"login"]) { //获取URL上面的参数 NSDictionary *params = [self getParams:[url query]]; BOOL status = [self login:[params objectForKey:@"name"] password:[params objectForKey:@"password"]]; if(status) { //调用JS回调 [webView stringByEvaluatingJavaScriptFromString:@"alert('登录成功!')"]; } else { [webView stringByEvaluatingJavaScriptFromString:@"alert('登录失败!')"]; } } return NO; } return YES; } |
1、同步和异步的问题
(1)Objective-C调用JavaScript代码的时候是同步的
- (NSString *)stringByEvaluatingJavaScriptFromString:(NSString *)script;
(2)JavaScript调用Objective-C代码的时候是异步的
- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType;
2、常见的JS调用
(1)获取页面title
NSString *title = [webview stringByEvaluatingJavaScriptFromString:@"document.title"];
(2)获取当前的URL
NSString *url = [webview stringByEvaluatingJavaScriptFromString:@"document.location.href"];
3、使用第三方库
https://github.com/marcuswestin/WebViewJavascriptBridge
使用案例
1、动态将网页上的图片全部缩放JavaScript脚本如下:
<span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">1</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">2</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">3</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">4</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">5</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">6</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">7</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">8</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">9</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">10</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">11</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">12</span> | function ResizeImages() { var myImg, oldWidth; var maxWidth = 320; for(i = 0; i < document.images.length; i++) { myImg = document.images[i]; if(myImg.width > maxWidth) { oldWidth = myImg.width; myImg.width = maxWidth; myImg.heith = myImg.height*(maxWidth/oldWidth); } } } |
<span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">1</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">2</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">3</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">4</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">5</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">6</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">7</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">8</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">9</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">10</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">11</span> <span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">12</span><span class="line-number" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; color: rgb(88, 110, 117) !important;">13</span> | [webView stringByEvaluatingJavaScriptFromString: @"var script = document.createElement('script');" "script.type = 'text/javascript';" "script.text = \"function ResizeImages() { " "var myimg,oldwidth;" "var maxwidth=380;" //缩放系数 "for(i=0;i <document.images.length;i++){" "myimg = document.images[i];" "if(myimg.width > maxwidth){" "oldwidth = myimg.width;" "myimg.width = maxwidth;" "myimg.height = myimg.height * (maxwidth/oldwidth);" "}" "}" "}\";" "document.getElementsByTagName('head')[0].appendChild(script);"]; [webView stringByEvaluatingJavaScriptFromString:@"ResizeImages();"]; |
参考资料
1、《关于UIWebView和PhoneGap的总结》2、《iOS开发之Objective-C与JavaScript的交互
》
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