ios 根據手勢放大或縮小圖片

1.在.h檔案中加入一個變數用來記錄當前的scale值, 讓這個ViewController遵循

UIGestureRecognizerDelegate代理.

並在.h中加入下面這個變數

CGFloat lastScale;

2. 在viewDidLoad中加入下面語句

    UIView *holderView = [[UIViewalloc]initWithFrame:CGRectMake(0,0,320,
416)];

    

   
UIImageView *showImgView = [[UIImageViewalloc]initWithFrame:CGRectMake(0,0,320,
416)];

    showImgView.image =img;

    showImgView.contentMode =UIViewContentModeScaleAspectFit;

    [holderView
addSubview:showImgView];

    [showImgView
release];    

    

   UIPinchGestureRecognizer *pinchRecognizer = [[UIPinchGestureRecognizeralloc]initWithTarget:selfaction:@selector(scaGesture:)];

    [pinchRecognizersetDelegate:self];

    [holderView
addGestureRecognizer:pinchRecognizer];

    [pinchRecognizerrelease];

    

    [self.viewaddSubview:holderView];

    [holderView
release];

3.在加入這個手勢的執行方法

-(void)scaGesture:(id)sender {

    [self.viewbringSubviewToFront:[(UIPinchGestureRecognizer*)senderview]];

   //當手指離開螢幕時,將lastscale設定為1.0

   if([(UIPinchGestureRecognizer*)senderstate]
== UIGestureRecognizerStateEnded) {

       
lastScale = 1.0;

       
return;

    }

    

   
CGFloat scale = 1.0 - (lastScale - [(UIPinchGestureRecognizer*)senderscale]);

   CGAffineTransform currentTransform = [(UIPinchGestureRecognizer*)senderview].transform;

   
CGAffineTransform newTransform = CGAffineTransformScale(currentTransform, scale, scale);

    [[(UIPinchGestureRecognizer*)senderview]setTransform:newTransform];

   lastScale = [(UIPinchGestureRecognizer*)senderscale];

}

4. 加入手勢的代理方法

#pragma mark - UIGestureRecognizerDelegate

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer 

shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {

   
return ![gestureRecognizer isKindOfClass:[UIPanGestureRecognizerclass]];

}

5、運行程式，效果(注意這裡只能是以圖片中心放大的，不能進行移動圖片，若要移動圖片，需要修改其Transform部分代碼)

下面這個圖是從別處找來的，
自己並上傳比較麻煩， 呵呵

注意：請在真機上運行，在模擬器中無法類比Pinch手勢， 按住option和shift鍵在模擬器上也能類比出兩個手指的手勢