UIScrollView在滚动时取消UIPageViewController手势 [英] UIScrollView cancels UIPageViewController gestures when scrolling

问题描述

我有一个 UIPageViewController 来处理我的书翻页。但是，每个图书页面都是 ViewController ，其中 UIScrollView 作为子视图。由于 contentSize ， UIScrollView 只能垂直滚动。问题是，当用户垂直滚动 scrollview 时，由于 scrollview 仍在滚动/减速，用户无法翻页。一个非常简单的方法是滚动页面，然后尝试点击视图的边缘。这通常会更改页面，并且当 scrollview 未移动时，它确实会更改页面。但是，当它移动时，水龙头会使滚动视图停止移动而不是翻页。

如果 UIPageViewController scrollviews 手势>是否试图通过点击或平移页面来使用手势来翻页以导致翻页动画？

有关我想要实现的行为的示例，检查iPhone上的Twitter官方客户端。
从滚动开始减速时，可以从时间轴滑动到发现。

解决方案

A UIScrollView 滚动事件将阻止其他 UIView 动画，所以在Twitter的情况下，他们可能会在一瞬间取消滚动滑动视图。正如您在问题中提到的那样：

如果UIPageViewController尝试使用手势通过点击来翻页，如何取消滚动视图手势或平移页面以使页面转动动画？

我建议解决方法。

不要依赖 UIPageViewController 的固有 UIPanGestureRecognizer ，而是包含您自己的 UIPanGestureRecognizer 在页面视图中，以便在页面的相应部分中检测到平移并在适当的方向上执行时，新的 UIPanGestureRecognizer 将覆盖 UIPageViewController 的 UIGestureRecognizer s并触发必要的操作。具体来说，你需要：

（1）暂停滚动动画

  CGPoint offset = scrollView.contentOffset; 
 [scrollView setContentOffset：offset animated：NO]; 
  

（2）使用

<以编程方式翻页pre> - （void）setViewControllers：（NSArray *）viewControllers方向：
（UIPageViewControllerNavigationDirection）方向动画：
（BOOL）动画完成：（void（^）（ BOOL完成））完成;


以便停止滚动动画并在一个流体平移手势内完成翻页。 / p>

I have a UIPageViewController that handles turning the pages of my "book". However, each book page is a ViewController with a UIScrollView as a subview. The UIScrollView is only able to scroll vertically due to the contentSize. The problem is that while the user scrolls the scrollview vertically, as the scrollview is still scrolling/decelerating the user can not turn the page. A very easy way to see this is to scroll the page and then try to tap the edge of the view. This would normally change the page, and it does change the page when the scrollview is not moving. However, when it is moving, the tap causes the scrollview to stop moving instead of turn the page.

How do I cancel the scrollviews gestures if the UIPageViewController is trying to use the gesture to turn the page by tapping or panning the page to cause the page turn animation?

For an example of the behavior I want to achieve, check the Twitter's official client on the iPhone. It's possible to swipe from Timeline to Discover while the feed is still decelerating from scrolling.

解决方案

A UIScrollView scroll event will block other UIView animations, so in the case of Twitter, they're probably canceling the scroll a split second before swiping the view. As you've asked in your question:

"How do I cancel the scrollviews gestures if the UIPageViewController is trying to use the gesture to turn the page by tapping or panning the page to cause the page turn animation?"

I'll suggest a workaround.

Instead of relying on the UIPageViewController's inherent UIPanGestureRecognizer, include your own UIPanGestureRecognizer in the page view so that when a pan is detected in the appropriate section of the page and performed in the appropriate direction, that new UIPanGestureRecognizer overrides the UIPageViewController's UIGestureRecognizers and triggers the necessary actions. Specifically, you need to:

(1) Halt the scrolling animation using

CGPoint offset = scrollView.contentOffset;
[scrollView setContentOffset:offset animated:NO];

(2) Turn the page programmatically using

- (void)setViewControllers:(NSArray *)viewControllers direction:
  (UIPageViewControllerNavigationDirection)direction animated:
  (BOOL)animated completion:(void (^)(BOOL finished))completion;

so that both the scrolling animation is halted and the page flip is completed within one fluid pan gesture.

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