在webView 加载html Finish后，使用javaScript 修改image的样式，达到图片自适应屏幕，代码具体如下：
NSString *js=@"var script = document.createElement('script');"
"script.type = 'text/javascript';"
"script.text = \"function ResizeImages() { "
"var myimg,oldwidth;"
"var maxwidth = %f;"
"for(i=0;i
"myimg = document.images[i];"
"if(myimg.width > maxwidth){"
"oldwidth = myimg.width;"
"myimg.width = %f;"
"}"
"}"
"}\";"
"document.getElementsByTagName('head')[0].appendChild(script);";
js = [NSString stringWithFormat:js,[UIScreen mainScreen].bounds.size.width,[UIScreen mainScreen].bounds.size.width-15];
[webView evaluateJavaScript:js completionHandler:nil];
[webView evaluateJavaScript:@"ResizeImages();"completionHandler:nil];
