手势--UIGestureRecognizer

监听触摸事件的做法:

1.如果想监听一个view上面的触摸事件,之前的做法是:
1>自定义一个view
2>实现view的touches的方法,在方法内部实现具体处理代码

2.通过touches方法监听view触摸事件,有很明显的几个缺点
1>必须得自定义view
2>由于是在view内部的touches方法中监听触摸事件,默认情况下,是无法让其他外界对象监听view的触摸事件
3>不容易区分用户的具体手势行为

iOS 3.2之后,苹果退出了手势识别功能(Gesture Recognizer),在触摸手势处理方面,大大简化了开发者的开发难度

UIGestureRecognizer---手势识别器

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手势行为
1.UITapGestureRecognizer 点击行为
2.UIPinchGestureRecognizer 捏合行为,用于缩放
3.UIPanGestureRecognizer 拖拽行为
4.UISwipeGestureRecognizer 轻扫行为
5.UIRotationGestureRecognizer 旋转行为
6.UILongPressGestureRecognizer 长按行为

手势识别器的用法:以UITapGestureRecognizer为例

1.创建手势识别器对象 (可以直接添加代理,和执行的方法)
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc]init] [tap addTarget:self action:]
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector()]

2.设置手势识别器对象的具体属性(一般不设置)

//连续敲击2次
tap.numberOfTapsRequired = 2;
//需要2根手指一起敲击
tap.numberOfTouchesRequired = 2;

3.添加手势识别器到对应的view上
[self.view addGestureRecognizer: tap]

手势识别的状态

typedef NS_ENUM(NSInteger,UIGestureRecognizerState)
{
    //没有触摸事件发生，所有手势识别的默认状态
    UIGestureRecognizerStatePossible,
    //一个手势已经开始但尚未改变或者完成时
    UIGestureRecognizerStateBegan,
    //手势状态改变
    UIGestureRecognizerStateChanged,
    //手势完成
    UIGestureRecognizerStateEnded,
    //手势取消，恢复至Possible状态
    UIGestureRecognizerStateCancelled,
    //手势失败，恢复至Possible状态
    UIGestureRecognizerStateFailed,
}

Snip20151007_8.png

手势的应用(点击手势)

- (void)viewDidLoad {
    [super viewDidLoad];
  
    // 建立点击手势，并制定target ，并要求实现tap方法
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tap)];
    // 将点击手势，加入_imageView的处理中, 记得一定要选择交互  ，  因为默认情况下 imageView的交互为no
    [_imageView addGestureRecognizer:tap];
    // 设置点击手势的代理，可以做一些特定的事情
    tap.delegate = self;
}

// 点击手势的范围缩减， 只接受图片一半的尺寸。
- (BOOL)gestureRecognizer:(nonnull UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(nonnull UITouch *)touch
{
     CGPoint tapP = [touch locationInView:_imageView];
    if (tapP.x < _imageView.frame.size.width * 0.5) {
        return YES;
    }
    return NO;

}

// 实现点击手势，方法
- (void)tap{

    NSLog(@"%s",__func__);

}

- (BOOL)gestureRecognizer:(nonnull UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(nonnull UITouch *)touch此方法可以设置允许手势的区域 ,默认为YES.

长按和轻扫手势.

#pragma mark - <轻扫手势>
- (void)setupSwipe
{

    // 多加几个轻扫手势，便能够实现多个方向的轻扫。
    UISwipeGestureRecognizer *swipe = [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(swipe)];
    
    [_imageView addGestureRecognizer:swipe];
    // 修改轻扫的的方向
    swipe.direction = UISwipeGestureRecognizerDirectionLeft;
    
    UISwipeGestureRecognizer *swipe1 = [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(swipe)];
    
    [_imageView addGestureRecognizer:swipe1];
    // 修改轻扫的的方向
    swipe1.direction = UISwipeGestureRecognizerDirectionRight;
    

}
- (void)swipe
{

    NSLog(@"%s",__func__);
}


#pragma mark - <长按点击>
- (void)setupLongPress
{
    UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc]initWithTarget:self action:@selector(longPress:)];
    
    [_imageView addGestureRecognizer:longPress];
    longPress.delegate = self;
}
- (void)longPress:(UILongPressGestureRecognizer *)longPress
{
    
    // 传入参数， 当前的手势，  手势状态，决定事件
    if (longPress.state == UIGestureRecognizerStateBegan) {
     NSLog(@"%s",__func__);
    }
}

捏合,拖拽手势
- (BOOL)gestureRecognizer:(nonnull UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(nonnull UIGestureRecognizer *)otherGestureRecognizer
默认为NO, 返回YES是允许多重手势.

// 允许组合手势
- (BOOL)gestureRecognizer:(nonnull UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(nonnull UIGestureRecognizer *)otherGestureRecognizer
{
    
    return YES;


}

#pragma mark - <旋转>
- (void)setupRotation
{

    UIRotationGestureRecognizer *rotation = [[UIRotationGestureRecognizer alloc]initWithTarget:self action:@selector(rotation:)];
    
    [_imageView addGestureRecognizer:rotation];
    
    rotation.delegate = self;

}

- (void)rotation:(UIRotationGestureRecognizer*)rotation
{
    CGFloat rotationF = rotation.rotation;
    
    _imageView.transform = CGAffineTransformRotate(_imageView.transform, rotationF);
    
    
    rotation.rotation = 0;


}


#pragma mark - <捏合>
- (void)setupPinch
{
    UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc]initWithTarget:self action:@selector(pinch:)];
    
    [_imageView addGestureRecognizer:pinch];
    
    pinch.delegate = self;

}

- (void)pinch:(UIPinchGestureRecognizer *)pinch
{
    // 获取捏合比例
    CGFloat scale = pinch.scale;
    
    _imageView.transform = CGAffineTransformScale(_imageView.transform, scale, scale);
    // 捏合后保持原比例，负责会变得不见得
    pinch.scale = 1;
    
}


#pragma mark - <拖拽>
- (void)setupPan
{

    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(pan:)];
    
    
    [_imageView addGestureRecognizer:pan];
    

}
- (void)pan:(UIPanGestureRecognizer *)pan
{
    CGPoint panP = [pan translationInView:_imageView];
    
    NSLog(@"%@",NSStringFromCGPoint(panP));
    
    // 如果不去让pan每次的tranlation为0 的话， 则再下次拖拽时 ，图片会直接回到初始位置，因为上一次的pan的translation没有清掉。
//    _imageView.transform = CGAffineTransformMakeTranslation(panP.x, panP.y);
    
    _imageView.transform = CGAffineTransformTranslate(_imageView.transform, panP.x, panP.y);

    // 每次拖拽，translation 设定为0  ，可以每次根据上一次的情况定位，去实现拖拽。
    [pan setTranslation:CGPointZero inView:_imageView];

}