捏合和点击手势无法正常工作

Posted 2023-03-16

【中文标题】捏合和点击手势无法正常工作

【英文标题】：Pinch and Tap Gestures don't work properly

【发布时间】：2013-12-16 13:32:52

【问题描述】：

我在 ViewController 中有一个 ImageView，我想用捏手势放大或缩小。另外，我想在用户双击图像时获得初始视图。我按照本教程进行操作Make Gallery

如果我只使用捏合手势都可以正常工作，我可以放大直到达到最大缩放，我可以缩小直到达到最小缩放。正确的结果如下图所示。

虽然，如果我双击 ImageView，ImageView 会获得其初始格式（图 1），但无法识别最小缩放的实现，如果我继续使用捏合手势缩小，ImageView 会继续缩小，我得到此结果（图 2）：

这些是我处理事件的方法：

@interface ImageGalleryViewController ()


NSString *productName;
CGFloat previousScale;
CGFloat previousRotation;
CGFloat beginX;
CGFloat beginY;

CGFloat scale;
//CGFloat __previousScale;


- (void)viewDidLoad
[super viewDidLoad];
// Do any additional setup after loading the view.

   scale=1.0;

   UIPinchGestureRecognizer *pinchGesture = [[UIPinchGestureRecognizer alloc]       initWithTarget:self action:@selector(scaleImage:)];
   [self.view addGestureRecognizer:pinchGesture];

   UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(resetImage:)];
   tapGesture.numberOfTapsRequired=2;
   [self.view addGestureRecognizer:tapGesture];




 - (void)resetImage:(UITapGestureRecognizer *)recognizer
     [UIView animateWithDuration:0.3 animations:^() 

     self.view.transform = CGAffineTransformIdentity;

     ];
     self.bigImage.transform = CGAffineTransformIdentity;
     [self.bigImage setCenter: CGPointMake(self.view.frame.size.width/2,self.view.frame.size.height/2+32)];
     [UIView commitAnimations];
 

- (void)scaleImage:(UIPinchGestureRecognizer *)recognizer

     NSLog(@"Scale: %f", [recognizer scale]);
     if ([recognizer state] == UIGestureRecognizerStateBegan) 
        previousScale = scale;
     

     CGFloat currentScale = MAX(MIN([recognizer scale] * scale, 10), 1);
     CGFloat scaleStep = currentScale / previousScale;
     [self.view setTransform: CGAffineTransformScale(self.view.transform, scaleStep, scaleStep)];

    previousScale = currentScale;

    if ([recognizer state] == UIGestureRecognizerStateEnded ||
        [recognizer state] == UIGestureRecognizerStateCancelled ||
        [recognizer state] == UIGestureRecognizerStateFailed) 
    // Gesture can fail (or cancelled?) when the notification and the object is dragged simultaneously
        scale = currentScale;
        NSLog(@"Final scale: %f", scale);
    

如果初始右视图（第一张图像）已经实现，我该如何停止缩小？

【参考方案1】：

我不得不在 resetImage 方法中将变量 scale 重置为 1.0。所以现在它可以正常工作了。