ios - UIPinchGestureRecognizer 和 UIPanGestureRecognizer 可以合并吗？

Question

我正在努力尝试弄清楚是否有可能创建一个结合了 UIPinchGestureRecognizer 和 UIPanGestureRecognizer 的单一组合手势识别器。

我使用平移进行 View 平移，使用捏合进行 View 缩放。我正在进行增量矩阵串联以导出应用于 View 的最终转换矩阵。该矩阵具有比例和平移。使用单独的手势识别器会导致抖动的移动/缩放。不是我想要的。因此，我想在一个手势中处理一次缩放和平移的连接。有人可以阐明如何执行此操作吗？

Answer 1

6/14/14:更新了带有 ARC 的 iOS 7+ 示例代码。

UIGestureRecognizers 可以一起工作，你只需要确保你不会破坏当前 View 的转换矩阵。使用将变换作为输入的 CGAffineTransformScale 方法和相关方法，而不是从头开始创建它(除非您自己维护当前的旋转、缩放或平移。

下载Xcode项目

• Sample UIPinchGesture project on Github .

注意:iOS 7 在 IB 中应用了 Pan/Pinch/Rotate 手势的 UIView 时表现得很奇怪。 iOS 8 修复了它，但我的解决方法是像这个代码示例一样在代码中添加所有 View 。

演示视频

1. 将它们添加到 View 并符合 UIGestureRecognizerDelegate 协议(protocol)

   @interface ViewController () <UIGestureRecognizerDelegate>
   
   @end
   
   @implementation ViewController
   
   - (void)viewDidLoad
   {
       [super viewDidLoad];
   
       UIView *blueView = [[UIView alloc] initWithFrame:CGRectMake(100, 100, 150, 150)];
       blueView.backgroundColor = [UIColor blueColor];
       [self.view addSubview:blueView];
       [self addMovementGesturesToView:blueView];
   
       // UIImageView's and UILabel's don't have userInteractionEnabled by default!
       UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"BombDodge.png"]]; // Any image in Xcode project
       imageView.center = CGPointMake(100, 250);
       [imageView sizeToFit];
       [self.view addSubview:imageView];
       [self addMovementGesturesToView:imageView];
   
       // Note: Changing the font size would be crisper than zooming a font!
       UILabel *label = [[UILabel alloc] init];
       label.text = @"Hello Gestures!";
       label.font = [UIFont systemFontOfSize:30];
       label.textColor = [UIColor blackColor];
       [label sizeToFit];
       label.center = CGPointMake(100, 400);
       [self.view addSubview:label];
       [self addMovementGesturesToView:label];
   }
   
   - (void)addMovementGesturesToView:(UIView *)view {
       view.userInteractionEnabled = YES;  // Enable user interaction
   
       UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePanGesture:)];
       panGesture.delegate = self;
       [view addGestureRecognizer:panGesture];
   
       UIPinchGestureRecognizer *pinchGesture = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(handlePinchGesture:)];
       pinchGesture.delegate = self;
       [view addGestureRecognizer:pinchGesture];
   }
   

2. 实现手势方法

   - (void)handlePanGesture:(UIPanGestureRecognizer *)panGesture {
       CGPoint translation = [panGesture translationInView:panGesture.view.superview];
   
       if (UIGestureRecognizerStateBegan == panGesture.state ||UIGestureRecognizerStateChanged == panGesture.state) {
           panGesture.view.center = CGPointMake(panGesture.view.center.x + translation.x,
                                                panGesture.view.center.y + translation.y);
           // Reset translation, so we can get translation delta's (i.e. change in translation)
           [panGesture setTranslation:CGPointZero inView:self.view];
       }
       // Don't need any logic for ended/failed/canceled states
   }
   
   - (void)handlePinchGesture:(UIPinchGestureRecognizer *)pinchGesture {
   
       if (UIGestureRecognizerStateBegan == pinchGesture.state ||
           UIGestureRecognizerStateChanged == pinchGesture.state) {
   
           // Use the x or y scale, they should be the same for typical zooming (non-skewing)
           float currentScale = [[pinchGesture.view.layer valueForKeyPath:@"transform.scale.x"] floatValue];
   
           // Variables to adjust the max/min values of zoom
           float minScale = 1.0;
           float maxScale = 2.0;
           float zoomSpeed = .5;
   
           float deltaScale = pinchGesture.scale;
   
           // You need to translate the zoom to 0 (origin) so that you
           // can multiply a speed factor and then translate back to "zoomSpace" around 1
           deltaScale = ((deltaScale - 1) * zoomSpeed) + 1;
   
           // Limit to min/max size (i.e maxScale = 2, current scale = 2, 2/2 = 1.0)
           //  A deltaScale is ~0.99 for decreasing or ~1.01 for increasing
           //  A deltaScale of 1.0 will maintain the zoom size
           deltaScale = MIN(deltaScale, maxScale / currentScale);
           deltaScale = MAX(deltaScale, minScale / currentScale);
   
           CGAffineTransform zoomTransform = CGAffineTransformScale(pinchGesture.view.transform, deltaScale, deltaScale);
           pinchGesture.view.transform = zoomTransform;
   
           // Reset to 1 for scale delta's
           //  Note: not 0, or we won't see a size: 0 * width = 0
           pinchGesture.scale = 1;
       }
   }
   
   - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
       return YES; // Works for most use cases of pinch + zoom + pan
   }
   

资源

• Xcode Gesture Sample Project
• Apple's Gestures Guide