UIWebView配合js的使用

项目中经常会遇到利用UIWebView加载html，对html的操作主要是利用js来，比如改变字号，获取图片等等；

/***
 *   Set Font Size
 *
 */
function setFontSize(fontSizePercent){
        for (var i = 0; i< document.getElementById('webview_content_wrapper').childNodes.length; i++)
        { //遍历该元素下所有子元素
             document.getElementById('webview_content_wrapper').childNodes[i].style.fontSize=fontSizePercent+'pt';;
            
        }
}

//获取图片
function getImages(){
var objs = document.getElementsByTagName("img");
var imgScr = '';
for(var i=0;i<objs.length;i++){
imgScr = imgScr + objs[i].src + '+';
};
return imgScr;
};
//为图片添加点击事件
function registerImageClickAction(){
var imgs=document.getElementsByTagName("img");
var length=imgs.length;
for(var i=0;i<length;i++){
img=imgs[i];
img.onclick=function(){
window.location.href='image-preview:'+this.src}
}
}

- (void)webViewDidFinishLoad:(UIWebView *)webView {
//加载js文件
    NSString *UtilsJsPath = [[NSBundle mainBundle] pathForResource:@"MyUtilsJs" ofType:@"js"];
    NSString *rbJsString = [NSString stringWithContentsOfFile:UtilsJsPath encoding:NSUTF8StringEncoding error:nil];
    [webView stringByEvaluatingJavaScriptFromString:rbJsString];
//改变字体大小    
    NSString *jsString;
    if (fontBig)
    {
        jsString = [[NSString alloc] initWithFormat:@"setFontSize(\"%@\");",@"15"];
    }
    if (fontSmall)
    {
        jsString = [[NSString alloc] initWithFormat:@"setFontSize(\"%@\");",@"10"];
    }
    if (fontNormal)
    {
        jsString = [[NSString alloc] initWithFormat:@"setFontSize(\"%@\");",@"12"];
    }
    [_webView stringByEvaluatingJavaScriptFromString:jsString];

    

//浏览图片
    NSString *urlResurlt = [webView stringByEvaluatingJavaScriptFromString:@"getImages()"];
    _urlArray = [NSMutableArray arrayWithArray:[urlResurlt componentsSeparatedByString:@"+"]];
    if (_urlArray.count >= 2)
    {
        [_urlArray removeLastObject];
    }
     
    [webView stringByEvaluatingJavaScriptFromString:@"registerImageClickAction();"];
}