iOS UIPan手势识别器

示例

平移手势识别器可检测到拖动手势。以下示例将图像添加到视图控制器，并允许用户在屏幕上四处拖动图像。

目标C

- (void)viewDidLoad {
    [super viewDidLoad];
    
    UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"imageToDrag"]];
    [imageView sizeToFit];
   imageView.userInteractionEnabled= YES;
    [self.view addSubview:imageView];
    
    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)];
    [imageView addGestureRecognizer:pan];
}

- (void)handlePan:(UIPanGestureRecognizer *)recognizer {
    CGPoint translation = [recognizer translationInView:self.view];
    recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x,
                                         recognizer.view.center.y + translation.y);
    [recognizer setTranslation:CGPointZero inView:self.view];
}

迅速

override func viewDidLoad() {
    super.viewDidLoad()
    
    let imageView = UIImageView.init(image: UIImage.init(named: "imageToDrag"))
    imageView.sizeToFit()
   imageView.isUserInteractionEnabled= true
    self.view.addSubview(imageView)
    
    let pan = UIPanGestureRecognizer.init(target: self, action: #selector(handlePan(recognizer:)))
    imageView.addGestureRecognizer(pan)
}

func handlePan(recognizer: UIPanGestureRecognizer) {
    let translation = recognizer.translation(in: self.view)
    if let view =recognizer.view{
       view.center= CGPoint(x: view.center.x + translation.x, y: view.center.y + translation.y)
    }
    recognizer.setTranslation(CGPoint.zero, in: self.view)
}

注意：尽管UIPanGestureRecognizer对于检测任何拖动手势很有用，但是如果您只想检测基本手势（例如用户向左/向右或向上/向下拖动手指），请使用UISwipeGestureRecognizer。UIPanGestureRecognizer如果您需要访问诸如translationInView:或的方法，则是更好的选择velocityInView:。