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)

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。

• UITapGestureRecognizer
• UIPinchGestureRecognizer
• UIRotationGestureRecognizer
• UISwipeGestureRecognizer
• UIPanGestureRecognizer
• UILongPressGestureRecognizer

上面的手势对应的操作是：

• Tap（点一下）
• Pinch（二指往內或往外拨动，平时经常用到的缩放）
• Rotation（旋转）
• Swipe（滑动，快速移动）
• Pan （拖移，慢速移动）
• LongPress（长按）

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？

• 监视手势是否结束
• 监视触摸的速度

- (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：

• 计算速度向量的长度（估计大部分都忘了）这些知识了。
• 如果速度向量小于200，那就会得到一个小于的小数，那么滑行会很短
• 基于速度和速度因素计算一个终点
• 确保终点不会跑出父View的边界
• 使用UIView动画使view滑动到终点

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：

– touchesBegan:withEvent:
– touchesMoved:withEvent:
– 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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