UIGestureRecognizer手势

手势一共分为七种，每一个手势的类都是继承于UIGestureRecognizer，我们操作的时候是操作其子类
一个手势只能添加到一个视图上，如果添加到多个视图上，只能对最后添加的那个视图其效果

轻拍手势（点击）

- (void)viewDidLoad{
    
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapAction:)];
    //设置点击次数
    tap.numberOfTapsRequired = 2;//快速点击两次才能触发
    //设置点击手指个数
    tap.numberOfTouchesRquired = 2;//在模拟器上测试时，按住alt键可以唤出第二根手指，模拟器最多只能有两根；
    //UIImageView添加手势（需要打开交互userInteractionEnabled）
    UIImageView *imgView = [[UIImageView alloc] initWithFrame:CGRectMake:(50,50,50,50)];
    imgView.userInteractionEnabled = YES;
    imgView.backgroundColor = [UIColor redColor];
    [self.view addSubview:imgView];
    [imgView release];
    [imgView addGestureRecognizer:tap];
    [tap release];
}
//方法实现
- (void)tapAction:(UITapGestureRecognizer *)tap{
    //每个手势都自带一个属性 .view，返回的是这个手势所在的视图
    tap.view.frame = CGRectMake(0,0,100,100);
}

轻扫手势

- (void)viewDidLoad{
    UISwipeGestureRecognizer *swipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipeAction:)];
    //设置轻扫方向 默认方向是向右轻扫，一个轻扫手势只能支持一个方向
    swipe.direction = UISwipeGestureRecognizerDirectionDown;
    [imgView addGestureRecognizer:swipe];//在轻拍中进行过初始化
    [swipe release];
}
- (void)swipeAction:(UISwipeGestureRecognizer *)swipe{
    if (swipe.direction == UISwipeGestureRecognizerDirectionDown) {
        NSLog(@"轻扫");
    }
}

长按手势

- (void)viewDidLoad{
    UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPressAction:)];
    //设置长按时间
    longPress.minimumPressDuration = 1;
    [imgView addGestureRecognizer:longPress];
    [longPress release];
}
- (void)longPressAction:(UILongPressGestureRecognizer *)longPress{
    if (longPress.state == UIGestureRecognizerStateBegan) {//注1
        UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"提示" message:@"123" preferredStyle:UIAlertControllerStyleActionSheet];
        [self presentViewController:alert animated:YES completion:nil];
    }
}

平移手势

- (void)viewDidLoad{
    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panAction:)];
    [imgView addGestureRecognizer:pan];
    [pan release];    
}
- (void)panAction:(UIPanGestureRecognizer *)pan{
    if (pan.state == UIGestureRecognizerStateChanged) {//注1
        CGPoint point = [pan translationInView:pan.view];
        //transform是视图的一个重要属性
        //我们的平移、旋转、缩放，改变的都是视图的transform属性，我们用何种方法去改变它，取决于赋值符号右边调用的API
        pan.view.transform = CGAffineTransformTranslate(pan.view.transform,point.x,point.y);
        //重新置成0点，每一次平移的结束时的位置会变成下一次平移的起点
        [pan setTranslation:CGPointZero inView:pan.view];
    }
}

旋转手势

- (void)viewDidLoad{
    UIRotationGestureRecognizer *rotation = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotationAction:)];
    [imgView addGestureRecognizer:rotation];
    [rotation release];    
}
- (void)rotationAction:(UIRotationGestureRecognizer *)rotation{
    if (rotation.state == UIGestureRecognizerStateChanged) {
        rotation.view.transform = CGAffineTransformTranslate(rotation.view.transform,rotation.rotation);
        //同平移
        rotation.rotation = 0;
    }
}

缩放手势

- (void)viewDidLoad{
    UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinchAction:)];
    [imgView addGestureRecognizer:pinch];
    [pinch release];
}
- (void)pinchAction:(UIPinchGestureRecognizer *)pinch{
    if (pinch.state == UIGestureRecognizerStateChanged) {
        pinch.view.transform = CGAffineTransformScale(pinch.view.transform,pinch.scale,pinch.scale);
        //同平移
        pinch.scale = 1;
    }        
}

屏幕边缘平移手势

UIScreenEdgePanGestureRecognizer
平时基本不用；

注：

1.
每一个手势都有一个state属性，表示的是手势识别的不同的阶段
是一个枚举类型

typedef NS_ENUM(NSInteger, UIGestureRecognizerState) {
    UIGestureRecognizerStatePossible, //默认状态
    UIGestureRecognizerStateBegan,
    UIGestureRecognizerStateChanged,
    UIGestureRecognizerStateEnded,
    UIGestureRecognizerStateCancelled,
    UIGestureRecognizerStateFailed,
    UIGestureRecognizerStateRecognized = UIGestureRecognizerStateEnded
};

除了轻拍手势之外，其他的手势都是连续的手势，刚按下去的时候state的状态是Possible，还没有被识别当达到识别条件（如到达longPress的长按时间，或者rotation手势，开始旋转）后会进入状态Began，但这个状态只会保持一瞬，然后进入Changed状态。
所以我们需要按照需求进行判定，如上文的longPress手势会present一个alert出来，如果不进行判定，会多次触发，导致程序出错，所以我们要把判定条件设为Began，这样一次长按就只会触发一次；
注中注：swipe手势只会在�识别结束的时才会触发一次，所以不用进行判定
2.
我们可以看出tap手势是longPress手势的一部分，swipe手势是pan手势的一部分，如果一个视图上多个手势，系统默认就会忽略掉作为其他手势一部分的手势，为了防止这种情况，需要用到*(void)requireGestureRecognizerToFail:(UIGestureRecognizer )otherGestureRecognizer方法
这个方法是由手势调用传入一个手势作为参数，当后一个手势识别失败时才会执行前一个手势
例：
[pan requireGestureRecognizerToFail:swipe];
//只有在swipe手势识别失败后，才会触发pan手势的方法

参考资料

http://www.cnblogs.com/kenshincui/p/3950646.html
崔江涛（KenshinCui）