這是封裝的一個(gè)UITapGestureRecognizer呀袱，這里記錄一下

主要思路

點(diǎn)擊圖片的時(shí)候洛口，首先在window的keywindow上面再創(chuàng)建一個(gè)view慌烧，然后把圖片等比例放大炫乓，放到上面冀墨，然后操作捏合闸衫，移動(dòng)

UIWindow * window = [UIApplication sharedApplication].keyWindow;
    backView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, windowWidth, windowHeight)];
    backView.backgroundColor = [UIColor blackColor];
    backView.alpha = 0;
    [window addSubview:backView];
    
    UITapGestureRecognizer * tap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(hideBackView)];
    [backView addGestureRecognizer:tap];
    
    UIImageView * backImageView = (UIImageView *)self.view;
    oldRect = backImageView.frame;
    
    UIImageView * showImageView = [[UIImageView alloc]initWithFrame:[self.view convertRect:self.view.bounds toView:window]];
    showImageView.image = backImageView.image;
    showImageView.tag = 190231;
    showImageView.userInteractionEnabled = YES;
    [backView addSubview:showImageView];
    
    //縮放手勢(shì)
    UIPinchGestureRecognizer * pinch = [[UIPinchGestureRecognizer alloc]initWithTarget:self action:@selector(pinchAction:)];
    [showImageView addGestureRecognizer:pinch];
    
    //移動(dòng)手勢(shì)
    UIPanGestureRecognizer * pan = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(panAction:)];
    [showImageView addGestureRecognizer:pan];
//放大圖片的主要代碼
    [UIView animateWithDuration:0.3 animations:^{
      showImageView.frame = CGRectMake(0,(windowHeight - backImageView.image.size.height * windowWidth / backImageView.image.size.width) / 2, windowWidth, backImageView.image.size.height * windowWidth / backImageView.image.size.width);
        backView.alpha = 1;
        newRect = showImageView.frame;
    }];

下面是手勢(shì)完成的主要操作

縮放手勢(shì)這里關(guān)鍵是找到放大的比例,首先要理清楚要放大的倍數(shù)是多少，如果直接使用sender.scale 這樣就是在前一次放大的基礎(chǔ)上诽嘉，再次放大那么多倍蔚出，而我們實(shí)際要的效果是在前一次放大的基礎(chǔ)上弟翘，再放大移動(dòng)的數(shù)值，所以每次手指移動(dòng)放大的倍數(shù)應(yīng)該是上次的sender.scale值減去當(dāng)前的sender.scale

    UIImageView * showImageView = (UIImageView *)[backView viewWithTag:190231];
   if (sender.state == UIGestureRecognizerStateBegan) {
       pinchChangeValue = 1;
       return;
   }
   CGFloat change = 1 - (pinchChangeValue - sender.scale);
   showImageView.transform = CGAffineTransformScale(showImageView.transform, change, change);
   //記錄當(dāng)前比例
   pinchChangeValue = sender.scale;

移動(dòng)手勢(shì)

   //這里和縮放差不多相同的原理
    if (sender.state == UIGestureRecognizerStateBegan) {
        panChangeValueOld = sender.view.center;
        return;
    }
    if (sender.state == UIGestureRecognizerStateChanged) {
        CGPoint translation = [sender translationInView:self.view];
        float newY = panChangeValueOld.y + translation.y;
        float newX = panChangeValueOld.x + translation.x;
        sender.view.center = CGPointMake(newX, newY);
    }

最后是點(diǎn)擊收起圖片：
這里要處理兩次的隱藏骄酗，點(diǎn)擊的時(shí)候判斷圖片是否被放大了稀余，如果被縮放手勢(shì)放大的話，先變?yōu)辄c(diǎn)擊放大后的尺寸趋翻，再變?yōu)樵瘸叽缇α眨绻麤]有被縮放手勢(shì)放大，則直接變?yōu)樵瓉沓叽?/p>

    UIImageView * showImageView = (UIImageView *)[backView viewWithTag:190231];
    if (showImageView.frame.size.width > newRect.size.width) {
        [UIView animateWithDuration:0.3 animations:^{
            showImageView.frame = newRect;
        }];
    }else{
        [UIView animateWithDuration:0.3 animations:^{
            showImageView.frame = oldRect;
            backView.alpha = 0;
        } completion:^(BOOL finished) {
            [backView removeFromSuperview];
        }];
    }

本次練習(xí)的demo的地址：demo