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iOS手势识别的详细使用方法(拖动,缩放,旋转,点击,手势依赖,自定义手势)

时间：2021-06-12 08:12:43 | 栏目：iOS代码 | 点击：次

手势识别在iOS上非常重要,手势操作移动设备的重要特征,极大的增加了移动设备使用便捷性。

1、UIGestureRecognizer介绍

手势识别在iOS上非常重要，手势操作移动设备的重要特征，极大的增加了移动设备使用便捷性。

iOS系统在3.2以后，为方便开发这使用一些常用的手势，提供了UIGestureRecognizer类。手势识别UIGestureRecognizer类是个抽象类，下面的子类是具体的手势，开发这可以直接使用这些手势识别。

上面的手势对应的操作是：

UIGestureRecognizer的继承关系如下：

2、使用手势的步骤

使用手势很简单，分为两步：

创建手势实例。当创建手势时，指定一个回调方法，当手势开始，改变、或结束时，回调方法被调用。

添加到需要识别的View中。每个手势只对应一个View，当屏幕触摸在View的边界内时，如果手势和预定的一样，那就会回调方法。

ps：一个手势只能对应一个View，但是一个View可以有多个手势。

建议在真机上运行这些手势,模拟器操作不太方便，可能导致你认为手势失效。

3、Pan 拖动手势：

UIImageView *snakeImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"snake.png"]]; 
snakeImageView.frame = CGRectMake(50, 50, 100, 160); 
UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] 
                        initWithTarget:self 
                        action:@selector(handlePan:)];   
[snakeImageView addGestureRecognizer:panGestureRecognizer]; 
[self.view setBackgroundColor:[UIColor whiteColor]]; 
[self.view addSubview:snakeImageView];

新建一个ImageView，然后添加手势

回调方法：

- (void) handlePan:(UIPanGestureRecognizer*) recognizer 
{ 
  CGPoint translation = [recognizer translationInView:self.view]; 
  recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x, 
                  recognizer.view.center.y + translation.y); 
  [recognizer setTranslation:CGPointZero inView:self.view]; 
   
}

4、Pinch缩放手势

UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc] 
                            initWithTarget:self 
                            action:@selector(handlePinch:)];<p class="p1">[<span class="s1">snakeImageView</span> <span class="s2">addGestureRecognizer</span>:pinchGestureRecognizer];</p> 
- (void) handlePinch:(UIPinchGestureRecognizer*) recognizer 
{ 
  recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale); 
  recognizer.scale = 1; 
}

5、Rotation旋转手势

UIRotationGestureRecognizer *rotateRecognizer = [[UIRotationGestureRecognizer alloc] 
                         initWithTarget:self 
                         action:@selector(handleRotate:)]; 
[snakeImageView addGestureRecognizer:rotateRecognizer]; 
- (void) handleRotate:(UIRotationGestureRecognizer*) recognizer 
{ 
  recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation); 
  recognizer.rotation = 0; 
}

添加了这几个手势后，运行看效果，程序中的imageView放了一个

                   /^\/^\
                  _|__|  O|
         \/     /~     \_/ \
          \____|__________/  \
                 \_______      \
                         `\     \                 \
                           |     |                  \
                          /      /                    \
                         /     /                       \\
                       /      /                         \ \
                      /     /                            \  \
                    /     /             _----_            \   \
                   /     /           _-~      ~-_         |   |
                  (      (        _-~    _--_    ~-_     _/   |
                   \      ~-____-~    _-~    ~-_    ~-_-~    /
                     ~-_           _-~          ~-_       _-~ 
                        ~--______-~                ~-___-~

的图片，在模拟器上拖动是没问题的。缩放和旋转有点问题，估计是因为在模拟器上的模拟的两个接触点距离在imageView的边界外了，所以操作无效果。

建议在真机上运行这个手势。

在模拟器上缩放和选择的操作技巧：

可以把imageView的frame值设置大一点，按住alt键，按下触摸板(不按下不行)，这样就可以旋转和缩放了。

6、添加第二个ImagView并添加手势

记住：一个手势只能添加到一个View，两个View当然要有两个手势的实例了

- (void)viewDidLoad 
{ 
  [super viewDidLoad]; 
 
  UIImageView *snakeImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"snake.png"]]; 
  UIImageView *dragonImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"dragon.png"]]; 
  snakeImageView.frame = CGRectMake(120, 120, 100, 160); 
  dragonImageView.frame = CGRectMake(50, 50, 100, 160); 
  [self.view addSubview:snakeImageView]; 
  [self.view addSubview:dragonImageView]; 
   
  for (UIView *view in self.view.subviews) { 
    UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] 
                            initWithTarget:self 
                            action:@selector(handlePan:)]; 
     
    UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc] 
                              initWithTarget:self 
                              action:@selector(handlePinch:)]; 
     
    UIRotationGestureRecognizer *rotateRecognizer = [[UIRotationGestureRecognizer alloc] 
                             initWithTarget:self 
                             action:@selector(handleRotate:)]; 
     
    [view addGestureRecognizer:panGestureRecognizer]; 
    [view addGestureRecognizer:pinchGestureRecognizer]; 
    [view addGestureRecognizer:rotateRecognizer]; 
    [view setUserInteractionEnabled:YES]; 
  } 
  [self.view setBackgroundColor:[UIColor whiteColor]];    
}

多添加了一条龙的view，两个view都能接收上面的三种手势。运行效果如下：

7、拖动(pan手势)速度(以较快的速度拖放后view有滑行的效果)
如何实现呢？

- (void) handlePan:(UIPanGestureRecognizer*) recognizer 
{ 
  CGPoint translation = [recognizer translationInView:self.view]; 
  recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x, 
                    recognizer.view.center.y + translation.y); 
  [recognizer setTranslation:CGPointZero inView:self.view]; 
   
  if (recognizer.state == UIGestureRecognizerStateEnded) { 
     
    CGPoint velocity = [recognizer velocityInView:self.view]; 
    CGFloat magnitude = sqrtf((velocity.x * velocity.x) + (velocity.y * velocity.y)); 
    CGFloat slideMult = magnitude / 200; 
    NSLog(@"magnitude: %f, slideMult: %f", magnitude, slideMult); 
     
    float slideFactor = 0.1 * slideMult; // Increase for more of a slide 
    CGPoint finalPoint = CGPointMake(recognizer.view.center.x + (velocity.x * slideFactor), 
                     recognizer.view.center.y + (velocity.y * slideFactor)); 
    finalPoint.x = MIN(MAX(finalPoint.x, 0), self.view.bounds.size.width); 
    finalPoint.y = MIN(MAX(finalPoint.y, 0), self.view.bounds.size.height); 
     
    [UIView animateWithDuration:slideFactor*2 delay:0 options:UIViewAnimationOptionCurveEaseOut animations:^{ 
      recognizer.view.center = finalPoint; 
    } completion:nil]; 
     
  }

代码实现解析：

运行后，快速拖动图像view放开会看到view还会在原来的方向滑行一段路。

8、同时触发两个view的手势

手势之间是互斥的，如果你想同时触发蛇和龙的view，那么需要实现协议

UIGestureRecognizerDelegate，

@interface ViewController : UIViewController<UIGestureRecognizerDelegate> 
@end

并在协议这个方法里返回YES。

-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer 
{ 
  return YES; 
}

 把self作为代理设置给手势：

panGestureRecognizer.delegate = self; 
pinchGestureRecognizer.delegate = self; 
rotateRecognizer.delegate = self;

这样可以同时拖动或旋转缩放两个view了。

9、tap点击手势

这里为了方便看到tap的效果，当点击一下屏幕时，播放一个声音。

为了播放声音，我们加入AVFoundation.framework这个框架。

- (AVAudioPlayer *)loadWav:(NSString *)filename { 
  NSURL * url = [[NSBundle mainBundle] URLForResource:filename withExtension:@"wav"]; 
  NSError * error; 
  AVAudioPlayer * player = [[AVAudioPlayer alloc] initWithContentsOfURL:url error:&error]; 
  if (!player) { 
    NSLog(@"Error loading %@: %@", url, error.localizedDescription); 
  } else { 
    [player prepareToPlay]; 
  } 
  return player; 
}

我会在最后例子代码给出完整代码，添加手势的步骤和前面一样的。

#import <UIKit/UIKit.h> 
#import <AVFoundation/AVFoundation.h> 
 
@interface ViewController : UIViewController<UIGestureRecognizerDelegate> 
@property (strong) AVAudioPlayer * chompPlayer; 
@property (strong) AVAudioPlayer * hehePlayer; 
 
@end 
- (void)handleTap:(UITapGestureRecognizer *)recognizer { 
  [self.chompPlayer play]; 
}

运行，点一下某个图，就会播放一个咬东西的声音。

不过这个点击播放声音有点缺陷，就是在慢慢拖动的时候也会播放。这使得两个手势重合了。怎么解决呢？使用手势的：

requireGestureRecognizerToFail方法。

10、手势的依赖性

在viewDidLoad的循环里添加这段代码：

[tapRecognizer requireGestureRecognizerToFail:panGestureRecognizer];

意思就是，当如果pan手势失败，就是没发生拖动，才会出发tap手势。这样如果你有轻微的拖动，那就是pan手势发生了。tap的声音就不会发出来了。

11、自定义手势

自定义手势继承：UIGestureRecognizer，实现下面的方法：

?C touchesBegan:withEvent: 
?C touchesMoved:withEvent: 
?C touchesEnded:withEvent: 
- touchesCancelled:withEvent:

新建一个类，继承UIGestureRecognizer，代码如下：
.h文件

#import <UIKit/UIKit.h> 
typedef enum { 
  DirectionUnknown = 0, 
  DirectionLeft, 
  DirectionRight 
} Direction; 
 
@interface HappyGestureRecognizer : UIGestureRecognizer 
@property (assign) int tickleCount; 
@property (assign) CGPoint curTickleStart; 
@property (assign) Direction lastDirection; 
 
@end

.m文件

#import "HappyGestureRecognizer.h" 
#import <UIKit/UIGestureRecognizerSubclass.h> 
#define REQUIRED_TICKLES    2 
#define MOVE_AMT_PER_TICKLE   25 
 
@implementation HappyGestureRecognizer 
 
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { 
  UITouch * touch = [touches anyObject]; 
  self.curTickleStart = [touch locationInView:self.view]; 
} 
 
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { 
   
  // Make sure we've moved a minimum amount since curTickleStart 
  UITouch * touch = [touches anyObject]; 
  CGPoint ticklePoint = [touch locationInView:self.view]; 
  CGFloat moveAmt = ticklePoint.x - self.curTickleStart.x; 
  Direction curDirection; 
  if (moveAmt < 0) { 
    curDirection = DirectionLeft; 
  } else { 
    curDirection = DirectionRight; 
  } 
  if (ABS(moveAmt) < MOVE_AMT_PER_TICKLE) return; 
   
  // 确认方向改变了 
  if (self.lastDirection == DirectionUnknown || 
    (self.lastDirection == DirectionLeft && curDirection == DirectionRight) || 
    (self.lastDirection == DirectionRight && curDirection == DirectionLeft)) { 
     
    // 挠痒次数 
    self.tickleCount++; 
    self.curTickleStart = ticklePoint; 
    self.lastDirection = curDirection; 
     
    // 一旦挠痒次数超过指定数，设置手势为结束状态 
    // 这样回调函数会被调用。 
    if (self.state == UIGestureRecognizerStatePossible && self.tickleCount > REQUIRED_TICKLES) { 
      [self setState:UIGestureRecognizerStateEnded]; 
    } 
  } 
   
} 
 
- (void)reset { 
  self.tickleCount = 0; 
  self.curTickleStart = CGPointZero; 
  self.lastDirection = DirectionUnknown; 
  if (self.state == UIGestureRecognizerStatePossible) { 
    [self setState:UIGestureRecognizerStateFailed]; 
  } 
} 
 
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event 
{ 
  [self reset]; 
} 
 
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event 
{ 
  [self reset]; 
} 
 
@end

调用自定义手势和上面一样，回到这样写：

- (void)handleHappy:(HappyGestureRecognizer *)recognizer{ 
  [self.hehePlayer play]; 
}

手势成功后播放呵呵笑的声音。

在真机上运行，按住某个view，快速左右拖动，就会发出笑的声音了。

代码解析：

先获取起始坐标：curTickleStart

通过和ticklePoint的x值对比，得出当前的放下是向左还是向右。再算出移动的x的值是否比MOVE_AMT_PER_TICKLE距离大，如果太则返回。

再判断是否有三次是不同方向的动作，如果是则手势结束，回调。

源代码：源代码下载。

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