如何识别 UIScrollView 中的滑动手势

Question

我正在尝试识别 UIScrollView 中的左/右滑动手势。我尝试创建 UISwipeGestureRecognizers 并将它们与滚动视图相关联。它有效，但很少见。大多数时候我不会接到电话。为什么？

我怎样才能可靠地向左/向右滑动来工作？我可以使用手势识别器还是我必须自己在 touchesBegan/Ended 中处理它

谢谢

Answer 1

想通了。就我而言，我的 UIScrollView 包含一个允许缩放的 UIImage。显然，这意味着启用了滚动，并且 UIScrollView 无法区分滚动手势和滑动手势（下一张，上一张图片）。

在我的例子中，关键是当图像未放大时禁用滚动视图中的滚动，并在放大时重新启用它。这提供了预期的行为。

关键是将以下内容放入滚动视图的委托中：

- (void)scrollViewDidZoom:(UIScrollView *)scrollView {
  if (scrollView.zoomScale!=1.0) {
    // Zooming, enable scrolling
    scrollView.scrollEnabled = TRUE;
  } else {
    // Not zoomed, disable scrolling so gestures get used instead
    scrollView.scrollEnabled = FALSE;
  }
}

我还必须在禁用滚动的情况下初始化滚动视图。
要启用缩放，只需在委托调用中提供图像，

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
  // Return the scroll view
  return myImage;
}

并在 viewDidLoad 中为缩放设置一些参数并设置手势识别器

- (void)viewDidLoad {
  [super viewDidLoad];
  myScrollView.contentSize = CGSizeMake(myImage.frame.size.width, myImage.frame.size.height);
  myScrollView.maximumZoomScale = 4.0;
  myScrollView.minimumZoomScale = 1.0;
  myScrollView.clipsToBounds = YES;
  myScrollView.delegate = self;

  [myScrollView addSubview:myImage];
  [self setWantsFullScreenLayout:TRUE];

  myScrollView.scrollEnabled = FALSE; 
  UISwipeGestureRecognizer *recognizer = 
    [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
  recognizer.delaysTouchesBegan = TRUE;
  [myScrollView addGestureRecognizer:recognizer];
  [recognizer release];

  recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
  recognizer.direction = UISwipeGestureRecognizerDirectionLeft;
  [myScrollView addGestureRecognizer:recognizer];
  [recognizer release];
  [myScrollView delaysContentTouches];
}

Answer 2

UIScrollView *scrollView = ...
UISwipeGestureRecognizer *mySwipe = ...

解决此问题的正确解决方案是添加一行代码：

[scrollView.panGestureRecognizer requireGestureRecognizerToFail:mySwipe]

Swift 版本：

scrollView.panGestureRecognizer.requireGestureRecognizerToFail(mySwipe)

Swift4 版本：

scrollView.panGestureRecognizer.require(toFail: mySwipe!);

Answer 3

好帖子。

我正在做类似的事情（没有图像视图），如果 contentSize 小于高度，我基本上必须禁用滚动（我的滚动视图仅垂直滚动）。

if (scrollView.contentSize.height>scrollView.frame.size.height) {
    scrollView.scrollEnabled = YES;
}
else {
    scrollView.scrollEnabled = NO;
}

这对我有用

Answer 4

适合那些想要制作动画并自定义滑动手势识别器的人。

我们可以使用 UIScrollView 和 UIGestureRecognizer 委托：

 Class ViewController: UIViewController, UISCrollViewDelegate, UIGestureRecognizerDelegate { 


   override func viewDidLoad() {
    super.viewDidLoad()

    scrollView.delegate = self
    swipeLeft.delegate = self
    swipeRight.delegate = self

  }


  func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldReceive touch: UITouch) -> Bool {
    return true
  }

  func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
    return true
  }

  func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
    return scrollView.alwaysBounceHorizontal
  }


  func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {

    // Your custom animation at the end of scrolling.
  }
}