轉載自:  http://stackoverflow.com/questions/18239666/uiwebview-getting-image-url-with-elementfrompoint

-(void)longPressRecognized:(UILongPressGestureRecognizer*)gestureRecognizer {if(gestureRecognizer.state ==UIGestureRecognizerStateBegan){CGPoint point =[gestureRecognizer locationInView:webView];
    longpressTouchedPoint 
 
= point;// convert point from view to HTML coordinate systemCGSize viewSize =[webView frame].size;CGSize windowSize =[webView windowSize];CGFloat f = windowSize.width / viewSize.width;if([[[UIDevice currentDevice] systemVersion] doubleValue]>=5.){
        point.x = point.x * f;
        point.y = point
 
.y * f;}else{// On iOS 4 and previous, document.elementFromPoint is not taking// offset into account, we have to handle itCGPoint offset =[webView scrollOffset];
        point.x = point.x * f + offset.x;
        point.y = point.y * f + offset.y;}// Load the JavaScript code from the Resources and inject it into the web page
 
NSString*path =[[NSBundle mainBundle] pathForResource:@"JSTools" ofType:@"js"];NSString*jsCode =[NSString stringWithContentsOfFile:path encoding:NSUTF8StringEncoding error:nil];[webView stringByEvaluatingJavaScriptFromString: jsCode];// call js functionsNSString*tags =[webView stringByEvaluatingJavaScriptFromString:[NSString stringWithFormat:@"getHTMLElementsAtPoint(%i,%i);",(NSInteger)point.x,(NSInteger)point.y]];NSString*tagsSRC =[webView stringByEvaluatingJavaScriptFromString:[NSString stringWithFormat:@"getLinkSRCAtPoint(%i,%i);",(NSInteger)point.x,(NSInteger)point.y]];NSLog(@"src : %@",tags);NSLog(@"src : %@",tagsSRC);NSString*url = nil;if([tags rangeOfString:@",IMG,"].location !=NSNotFound){
        url = tagsSRC;// Here is the image url!}

function getHTMLElementsAtPoint(x,y){
var tags ="";
var e;
var offset =0;while((tags.search(",(A|IMG),")<0)&&(offset <20)){
    tags =",";
    e = document.elementFromPoint(x,y+offset);while(e){if(e.tagName){
            tags += e.tagName +',';}
        e = e.parentNode;}if(tags.search(",(A|IMG),")<0){
        e = document.elementFromPoint(x,y-offset);while(e){if(e.tagName){
                tags += e.tagName +',';}
            e = e.parentNode;}}

    offset++;}return tags;}

function getLinkSRCAtPoint(x,y){
var tags ="";
var e ="";
var offset =0;while((tags.length ==0)&&(offset <20)){
    e = document.elementFromPoint(x,y+offset);while(e){if(e.src){
            tags += e.src;break;}
        e = e.parentNode;}if(tags.length ==0){
        e = document.elementFromPoint(x,y-offset);while(e){if(e.src){
                tags += e.src;break;}
            e = e.parentNode;}}
    offset++;}return tags;}