Gesture Recognizer <手势识别功能> iOS 3.2之后

• touches方法监听view触摸事件的缺点

  • 必须得自定义view

  • 由于是在view内部的touches方法中监听触摸事件，因此默认情况下，无法让其他外界对象监听view的触摸事件

  • 不容易区分用户的具体手势行为

UIGestureRecognizer

• 为了完成手势识别，必须借助于手势识别器----UIGestureRecognizer

• 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

UITapGestureRecognizer(敲击)
UIPinchGestureRecognizer(捏合，用于缩放)
UIPanGestureRecognizer(拖拽)
UISwipeGestureRecognizer(轻扫)
UIRotationGestureRecognizer(旋转)
UILongPressGestureRecognizer(长按)

• 每一个手势识别器的用法都差不多，比如UITapGestureRecognizer的使用步骤如下

创建手势识别器对象
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] init];

设置手势识别器对象的具体属性
// 连续敲击2次
tap.numberOfTapsRequired = 2;
// 需要2根手指一起敲击
tap.numberOfTouchesRequired = 2;

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

监听手势的触发
[tap addTarget:self action:@selector(tapIconView:)];

• 手势识别状态

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,
    // 识别到手势识别
    UIGestureRecognizerStateRecognized = UIGestureRecognizerStateEnded
};

• 代理方法

// 是否允许开始触发手势
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{
    return NO;
}

// 是否允许同时支持多个手势，默认是不支持多个手势
// 返回yes表示支持多个手势
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    return YES;
}

// 是否允许接收手指的触摸点
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch{
    // 获取当前的触摸点
    CGPoint curP = [touch locationInView:self.imageView];

    if (curP.x < self.imageView.bounds.size.width * 0.5) {
        return NO;
    }else{
        return YES;
    }
}

• 点按手势

- (void)setUpTap
{
    // 创建点按手势
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tap:)];

    tap.delegate = self;

    [_imageView addGestureRecognizer:tap];
}

• 长按手势

  • UILongPressGestureRecognizer
  • 默认会触发两次
  • longPress.state == UIGestureRecognizerStateBegan,这个状态选择触发哪一次

• 轻扫

- (void)setUpSwipe
{
    // 默认轻扫的方向是往右
    UISwipeGestureRecognizer *swipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipe)];

    swipe.direction = UISwipeGestureRecognizerDirectionUp;

    [self.imageView addGestureRecognizer:swipe];

    // 如果以后想要一个控件支持多个方向的轻扫，必须创建多个轻扫手势，一个轻扫手势只支持一个方向
    // 默认轻扫的方向是往右
    UISwipeGestureRecognizer *swipeDown = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipe)];

    swipeDown.direction = UISwipeGestureRecognizerDirectionDown;

    [self.imageView addGestureRecognizer:swipeDown];


}

• 旋转手势

  • UIRotationGestureRecognizer

 // 默认传递的旋转的角度都是相对于最开始的位置
- (void)rotation:(UIRotationGestureRecognizer *)rotation
{

    self.imageView.transform = CGAffineTransformRotate(self.imageView.transform, rotation.rotation);

    // 复位
    rotation.rotation = 0;

    // 获取手势旋转的角度
    NSLog(@"%f",rotation.rotation);
}

• 捏合

  • UIPinchGestureRecognizer

• 拖拽

- (void)setUpPan
{
    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];


    [self.imageView addGestureRecognizer:pan];
}

- (void)pan:(UIPanGestureRecognizer *)pan
{
    // 获取手势的触摸点
   // CGPoint curP = [pan locationInView:self.imageView];

    // 移动视图
    // 获取手势的移动，也是相对于最开始的位置
    CGPoint transP = [pan translationInView:self.imageView];

    self.imageView.transform = CGAffineTransformTranslate(self.imageView.transform, transP.x, transP.y);

    // 复位
    [pan setTranslation:CGPointZero inView:self.imageView];

  //  NSLog(@"%@",NSStringFromCGPoint(curP));
}