一.手势识别理论

1. UIGestureRecognizer手势识别器

利用UIGestureRecognizer，能轻松识别用户在某个view上面做的一些常见手势

UIGestureRecognizer是一个抽象类，定义了所有手势的基本行为，使用它的子类才能处理具体的手势

2. 触摸手指类型

UITapGestureRecognizer(敲击)

UIPinchGestureRecognizer(捏合，用于缩放)

UIPanGestureRecognizer(拖拽)

UISwipeGestureRecognizer(轻扫)

UIRotationGestureRecognizer(旋转)

UILongPressGestureRecognizer(长按)

3.手势使用方法

1> 创建手势并监听

2> 添加手势

3> 实现手势方法

二. 手势识别代码

1. 点击/敲击 : UITapGestureRecognizer

1> 创建

- (void)setUpTap
{
 // 点击
 UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tap:)];
 [self.imageView addGestureRecognizer:tap];
 
    tap.delegate = self;
}

2 > 实现方法

- (void)tap:(UITapGestureRecognizer *)tap
{
 NSLog(@"%s", __func__);
}

3> 点击手势成为代理<UIGestureRecognizerDelegate>,实现shouldReceiveTouch,可设定某些范围可以点击

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch
{
 // 获取当前点的位置
 CGPoint curP = [touch locationInView:self.imageView];
 
 if (curP.x > self.imageView.bounds.size.width * 0.5) { // 右边不可接受点击事件
 return NO;
 } else { // 左边可以接受点击事件
 return YES;
 }
}

2. 捏合(放大/缩小) : UIPinchGestureRecognizer

1> 对象创建

// 捏合
UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinch:)];

pinch.delegate = self;

[self.imageView addGestureRecognizer:pinch];

2> 实现监听方法 缩放属性: @property (nonatomic) CGFloat scale;

- (void)pinch:(UIPinchGestureRecognizer *)pinch
{
 // 捏合缩放
    self.imageView.transform = CGAffineTransformScale(self.imageView.transform, pinch.scale, pinch.scale);
 // 恢复缩放
 [pinch setScale:1];
}

3. 旋转 : UIRotationGestureRecognizer

1> 对象创建

// 旋转
UIRotationGestureRecognizer *rotation = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotation:)];

rotation.delegate = self;

[self.imageView addGestureRecognizer:rotation];

2> 实现监听方法 旋转属性: @property (nonatomic) CGFloat rotation;

- (void)rotation:(UIRotationGestureRecognizer *)rotation
{
    self.imageView.transform = CGAffineTransformRotate(self.imageView.transform, rotation.rotation);


           // 旋转清零

 [rotation setRotation:0];
}

4. 拖动(移动) : UIPanGestureRecognizer

1> 对象创建

// 拖动
UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];
 
[self.imageView addGestureRecognizer:pan];

2> 实现监听方法 注:拖动距离需要清零

- (void)pan:(UIPanGestureRecognizer *)pan
{
 // 计算拖动距离(相对于初始位置)
 CGPoint transP = [pan translationInView:self.imageView];
 
    self.imageView.transform = CGAffineTransformTranslate(self.imageView.transform, transP.x, transP.y);
 
 // 拖动距离请0
 [pan setTranslation:CGPointZero inView:self.imageView];
}

5. 轻扫手势 : UISwipeGestureRecognizer

1> 对象创建

// 滑动 (默认向右滑)
UISwipeGestureRecognizer *swipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipe:)];
 
// 设置滑动方向
 /*
     UISwipeGestureRecognizerDirectionRight = 右滑
     UISwipeGestureRecognizerDirectionLeft  = 左滑
     UISwipeGestureRecognizerDirectionUp    = 上滑
     UISwipeGestureRecognizerDirectionDown  = 下滑
     */
swipe.direction = UISwipeGestureRecognizerDirectionUp;
 
[self.imageView addGestureRecognizer:swipe];

2> 实现监听方法

- (void)swipe:(UISwipeGestureRecognizer *)swipe
{
 NSLog(@"%s", __func__);
}

6. 长按 : UILongPressGestureRecognizer

1> 对象创建

//1.创建长按手势
UILongPressGestureRecognizer *longP = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longP:)];

//2.添加手势
[self.imageV addGestureRecognizer:longP];

2> 实现监听方法

//当手指长按的时候调用,注意当长按时,手指移动的时候,会持续调用这个方法,当手指离开时也会调用这个方法.
- (void)longP:(UILongPressGestureRecognizer *)longP{
 /*
     UIGestureRecognizerStatePossible
 
     UIGestureRecognizerStateBegan = 开始长按
     UIGestureRecognizerStateChanged = 长按移动
     UIGestureRecognizerStateEnded = 长按结束
     UIGestureRecognizerStatePossible
     UIGestureRecognizerStateCancelled = 取消长按
     UIGestureRecognizerStatePossible
     UIGestureRecognizerStateFailed
     UIGestureRecognizerStateRecognized = UIGestureRecognizerStateEnded = 长按结束
     */
 if (longP.state == UIGestureRecognizerStateBegan) {
 NSLog(@"开始长按");
 }else if(longP.state == UIGestureRecognizerStateChanged){
 NSLog(@"长按时移动");
 }else if(longP.state == UIGestureRecognizerStateEnded){
 NSLog(@"手指离开");
 }
}

7. 旋转和捏合

1> 添加这2个手势,并设置代理

[self setUpRotation];
[self setUpPinch];

2> 实现代理方法允许多手势

// 允许多触摸事件
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
 return YES;
}