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)

UITapGestureRecognizer

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:)];

UIGestureRecognizerDelegate

#pragma mark - 手势代理方法
// 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;
//    }
//}

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

手势示例

#pragma mark - 点按手势
-(void)setUpTap{

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

    [self.seaImageView addGestureRecognizer:tap];
}

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

#pragma mark - 长按手势
// 注意点：默认会触发两次
- (void)setUpLongPress{
    UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPress:)];

    [self.seaImageView addGestureRecognizer:longPress];
}

- (void)longPress:(UILongPressGestureRecognizer *)longPress
{

    if (longPress.state == UIGestureRecognizerStateBegan) {

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

#pragma mark - 轻扫手势
- (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.seaImageView 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.seaImageView addGestureRecognizer:swipeDown];


}

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

#pragma mark - 旋转手势
- (void)setUpRotation{
    UIRotationGestureRecognizer *rotation = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotation:)];
    rotation.delegate = self;
    [self.seaImageView addGestureRecognizer:rotation];
}

// 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.seaImageView.transform = CGAffineTransformRotate(self.seaImageView.transform, rotation.rotation);

    // 复位
    rotation.rotation = 0;

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

#pragma mark - 捏合
- (void)setUpPinch
{
    UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinch:)];
    pinch.delegate = self;
    [self.seaImageView addGestureRecognizer:pinch];
}

- (void)pinch:(UIPinchGestureRecognizer *)pinch
{
    self.seaImageView.transform = CGAffineTransformScale(self.seaImageView.transform, pinch.scale, pinch.scale);

    // 复位
    NSLog(@"%f",pinch.scale);
    pinch.scale = 1;
}

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


    [self.seaImageView 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.seaImageView];

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

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

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