iOS-手势识别

/**
 1. 使用手势识别的四个步骤
 
 1> 实例化手势识别
    - (id)initWithTarget:(id)target action:(SEL)action;
 2> 设置手势识别属性
 3> 将手势识别附加到指定的视图
    addGestureRecognizer
 
 4> 编写监听方法
 
 用代码创建一个UIImageView添加到视图，实验6种手势识别。

 3. 手势说明
 
 0> UIGestureRecognizer     所有手势识别的父类，不允许直接使用，可以用来自定义手势（建议大家不要挑战）
 
    最常用的属性：
 
    view：   发生手势的视图
    state：  手势当前的状态，主要用于连续手势，对于离散手势一般不使用
 
 
 
 1> UITapGestureRecognizer          点按手势(离散手势，其他手势都是连续手势)
 
    属性：
    numberOfTapsRequired       点击次数，单击双击
    numberOfTouchesRequired    手指根数
 
 2> UILongPressGestureRecognizer    长按手势
 
    属性不建议修改
 
 3> UIPanGestureRecognizer          拖动手势
 
    属性：不常用
    方法：
    // 在视图中拖动的距离
    - (CGPoint)translationInView:(UIView *)view;
    // 在视图中拖动的速度，通常可用于模拟惯性，需要一些物理方面的计算
     - (CGPoint)velocityInView:(UIView *)view;
 
 4> UIPinchGestureRecognizer        捏合手势
 
    属性：
    scale           比例
    velocity        捏合速度，不常用
 
 5> UIRotationGestureRecognizer     旋转手势
 
    属性
    rotation        旋转角度
    velocity        旋转速度，不常用
 
 6> UISwipeGestureRecognizer        轻扫手势，通常添加到根视图上
    
    属性
    numberOfTouchesRequired     参与轻扫手势的手指根数
    direction                   轻扫的方向
 
    提示：
    1) 如果要检测几个方向的轻扫，需要分别实例化几个轻扫手势
    2) 轻扫手势虽然是连续手势，但是不需要去处理UIGestureRecognizerStateChanged状态
        因为是在手指离开屏幕后，该手势才被识别的
 
 其他技巧
 
    在if语句中，将常量放置在判断条件的左侧，可以避免因为只写了 = 出现警告，置之不理的情况！
 */

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    // 0. 实例化UIImageView
    UIImage *image = [UIImage imageNamed:@"001"];
    UIImageView *imageView = [[UIImageView alloc]initWithImage:image];
    
    [imageView setFrame:CGRectMake(10, 100, 300, 196)];
    [self.view addSubview:imageView];
    
    [imageView setUserInteractionEnabled:YES];
    
    // 1. 添加点按手势
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tap:)];
    // 定义双击
    tap.numberOfTapsRequired = 2;
    [imageView addGestureRecognizer:tap];
    
    // 2. 添加长按手势
    UILongPressGestureRecognizer *longTap = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longTap:)];
    [imageView addGestureRecognizer:longTap];
    
    // 3. 拖动手势
    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];
    
    [imageView addGestureRecognizer:pan];
    
    // 4. 捏合手势
    UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinch:)];
    [imageView addGestureRecognizer:pinch];
    
    // 5. 旋转手势
    UIRotationGestureRecognizer *rotation = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotate:)];
    [imageView addGestureRecognizer:rotation];
    
    // 6. 轻扫手势
    // 如果要做清扫手势，需要分别实例化4个方向的手势
    UISwipeGestureRecognizer *swipeUp = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipe:)];
    
    swipeUp.direction = UISwipeGestureRecognizerDirectionUp | UISwipeGestureRecognizerDirectionDown | UISwipeGestureRecognizerDirectionLeft | UISwipeGestureRecognizerDirectionRight;
    
    [self.view addGestureRecognizer:swipeUp];
    
//    UISwipeGestureRecognizer *swipeDown = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipe:)];
//    swipeDown.direction = UISwipeGestureRecognizerDirectionDown;
//    [self.view addGestureRecognizer:swipeDown];
//    
//    UISwipeGestureRecognizer *swipeLeft = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipe:)];
//    swipeLeft.direction = UISwipeGestureRecognizerDirectionLeft;
//    [self.view addGestureRecognizer:swipeLeft];
//
//    UISwipeGestureRecognizer *swipeRight = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipe:)];
//    swipeRight.direction = UISwipeGestureRecognizerDirectionRight;
//    [self.view addGestureRecognizer:swipeRight];
}

#pragma mark - 点按手势
- (void)tap:(UITapGestureRecognizer *)recognizer
{
    // 双击放大图片
    UIImageView *imageView = (UIImageView *)recognizer.view;

    [UIView animateWithDuration:0.8f animations:^{
        [imageView setTransform:CGAffineTransformScale(imageView.transform, 2.0, 2.0)];
    } completion:^(BOOL finished) {
        [UIView animateWithDuration:0.5f animations:^{
            [imageView setTransform:CGAffineTransformScale(imageView.transform, 0.5, 0.5)];
        }];
    }];
}

#pragma mark - 长按手势
- (void)longTap:(UILongPressGestureRecognizer *)recognizer
{
    NSLog(@"长按");
    // 长按旋转图片
    // 开始长按
    // 在形变时，iOS采取就近原则旋转，如果不能按照希望的方向旋转，可以增加一些修正值，例如0.01
    // 直接通过形变属性，要实现一次性转一圈，比较困难，可以分两次进行
    if (UIGestureRecognizerStateBegan == recognizer.state) {
        [UIView animateWithDuration:0.8f animations:^{
            [recognizer.view setTransform:CGAffineTransformRotate(recognizer.view.transform, M_PI - 0.01)];
        }];
    } else if (UIGestureRecognizerStateEnded == recognizer.state) {
        [UIView animateWithDuration:0.8f animations:^{
            [recognizer.view setTransform:CGAffineTransformRotate(recognizer.view.transform, M_PI - 0.01)];
        } completion:^(BOOL finished) {
            // 清除所有的形变属性
            [recognizer.view setTransform:CGAffineTransformIdentity];
        }];
    }
}

#pragma mark - 拖动
- (void)pan:(UIPanGestureRecognizer *)recognizer
{
    CGPoint translation = [recognizer translationInView:self.view];
    
    // 让图像根据手指移动
    if (UIGestureRecognizerStateChanged == recognizer.state) {
        // 形变参数，有Make的时候，是相对初始位置计算的
        // 没有Make是递增修改形变的
        [recognizer.view setTransform:CGAffineTransformTranslate(recognizer.view.transform, translation.x, translation.y)];
        
        // 拖动手指中的平移距离是相对于初始位置，如果使用CGAffineTransformTranslate累加形变方法
        // 需要在每次位移之后，重置recognizer的位移量，就是将位移量清零
        [recognizer setTranslation:CGPointZero inView:recognizer.view];
    }
}

#pragma mark - 捏合
- (void)pinch:(UIPinchGestureRecognizer *)recognizer
{
    // 调整图像的显示比例
    if (UIGestureRecognizerStateChanged == recognizer.state) {
        
        // 等比例缩放
        [recognizer.view setTransform:CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale)];
        
        // 在设置累加形变参数时，需要充值手势的缩放比例
        recognizer.scale = 1.0f;
    }
}

#pragma mark - 旋转
- (void)rotate:(UIRotationGestureRecognizer *)recognizer
{
    if (UIGestureRecognizerStateChanged == recognizer.state) {
        recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation);
        
        // 重置旋转量
        recognizer.rotation = 0.0f;
    }
}


#pragma mark - 轻扫
- (void)swipe:(UISwipeGestureRecognizer *)recognizer
{
    //NSLog(@"%d", recognizer.direction);
    if (UISwipeGestureRecognizerDirectionDown == recognizer.direction) {
        NSLog(@"向下");
    } else if (UISwipeGestureRecognizerDirectionUp == recognizer.direction) {
        NSLog(@"向上");
    } else if (UISwipeGestureRecognizerDirectionLeft == recognizer.direction) {
        NSLog(@"向左");
    } else if (UISwipeGestureRecognizerDirectionRight == recognizer.direction) {
        NSLog(@"向右");
    }
}