UIWebView之获取所点位置的图片(放大webView中的图片)

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    _showWebView = [[UIWebView alloc] initWithFrame:CGRectMake(0, 0, 320, 460-44)];
    NSURLRequest *urlRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://news.163.com/special/qingsongyike"]];
    [_showWebView loadRequest:urlRequest];
    [self.view addSubview:_showWebView];
    
    [self addTapOnWebView];
 }

-(void)addTapOnWebView
{
    UITapGestureRecognizer* singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleTap:)];
    [self.showWebView addGestureRecognizer:singleTap];
    singleTap.delegate = self;
    singleTap.cancelsTouchesInView = NO;
}

#pragma mark- TapGestureRecognizer
/**
 *  3.允许多个手势识别器共同识别
 
    默认情况下，两个gesture recognizers不会同时识别它们的手势,但是你可以实现UIGestureRecognizerDelegate协议中的
    gestureRecognizer:shouldRecognizeSimultaneouslyWithGestureRecognizer:方法对其进行控制。这个方法一般在一个手    势接收者要阻止另外一个手势接收自己的消息的时候调用，如果返回YES,则两个gesture recognizers可同时识别，如果返回NO，则     并不保证两个gesture recognizers必不能同时识别，因为另外一个gesture recognizer的此方法可能返回YES。也就是说两个
gesture recognizers的delegate方法只要任意一个返回YES，则这两个就可以同时识别；只有两个都返回NO的时候，才是互斥的。默认情况下是返回NO。
 *  如果不写这句话，会导致自己创建的手势不会响应事件，因为webView里的子控件自带很多手势。
 *  @param gestureRecognizer      手势
 *  @param otherGestureRecognizer 其他手势
 *
 *  @return YES代表可以多个手势同时识别，默认是NO，不可以多个手势同时识别
 */
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    return YES;
}

-(void)handleSingleTap:(UITapGestureRecognizer *)sender
{
    CGPoint pt = [sender locationInView:self.showWebView];
    NSString *imgURL = [NSString stringWithFormat:@"document.elementFromPoint(%f, %f).src", pt.x, pt.y];
    NSString *urlToSave = [self.showWebView stringByEvaluatingJavaScriptFromString:imgURL];
    NSLog(@"image url=%@", urlToSave);
    if (urlToSave.length > 0) {
        [self showImageURL:urlToSave point:pt];
    }
}

//呈现图片
-(void)showImageURL:(NSString *)url point:(CGPoint)point
{
    UIImageView *showView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 320, 470)];
    showView.center = point;
    [UIView animateWithDuration:0.5f animations:^{
        CGPoint newPoint = self.view.center;
        newPoint.y += 20;
        showView.center = newPoint;
    }];
    
    showView.backgroundColor = [UIColor blackColor];
    showView.alpha = 0.9;
    showView.userInteractionEnabled = YES;      
    [self.view addSubview:showView];
    [showView setImageWithURL:[NSURL URLWithString:url]];
    
    UITapGestureRecognizer* singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleViewTap:)];
    [showView addGestureRecognizer:singleTap];
    
    [self.navigationController setNavigationBarHidden:YES animated:YES];
}


//移除图片查看视图
-(void)handleSingleViewTap:(UITapGestureRecognizer *)sender
{    
    for (id obj in self.view.subviews) {
        if ([obj isKindOfClass:[UIImageView class]]) {
            [obj removeFromSuperview];
        }
    }
    [self.navigationController setNavigationBarHidden:NO animated:YES];
}