获取UIPageViewController的滚动位置 [英] Get scroll position of UIPageViewController

问题描述

我正在使用 UIPageViewController ，我需要在用户滑动时获取ViewController的滚动位置，这样我可以在视图转换到的时候部分淡化某些资源下一个 UIViewController 。

I am using a UIPageViewController, and I need to get the scroll position of the ViewController as the users swipe so I can partially fade some assets while the view is transitioning to the next UIViewController.

UIPageViewController的委托和数据源方法似乎没有提供对此的任何访问，并且在内部我假设 UIPageViewController 必须在某处使用滚动视图，但它似乎没有直接子类化它所以我无法调用

The delegate and datasource methods of UIPageViewController don't seem to provide any access to this, and internally I'm assuming that the UIPageViewController must be using a scroll view somewhere, but it doesn't seem to directly subclass it so I'm not able to call

func scrollViewDidScroll(scrollView: UIScrollView) {

}

我看过一些其他帖子建议获取对 pageViewController！.view.subviews 然后第一个索引是一个scrollView，但这似乎非常 hacky。我想知道是否有更标准的方法来处理这个问题。

I've seen some other posts suggestion to grab a reference to the pageViewController!.view.subviews and then the first index is a scrollView, but this seems very hacky. I'm wondering if there is a more standard way to handle this.

推荐答案

你可以在你的<$里面搜索UIScrollView C $ C> UIPageViewController 。要做到这一点，你必须实现 UIScrollViewDelegate 。

You can search for the UIScrollView inside your UIPageViewController. To do that, you will have to implement the UIScrollViewDelegate.

之后你可以得到你的scrollView：

After that you can get your scrollView:

for v in pageViewController.view.subviews{
    if v.isKindOfClass(UIScrollView){
        (v as UIScrollView).delegate = self
    }
}

之后，你是能够使用所有UIScrollViewDelegate方法，因此您可以覆盖 scrollViewDidScroll 方法，您可以在其中获取scrollPosition：

After that, you are able to use all the UIScrollViewDelegate-methods and so you can override the scrollViewDidScroll method where you can get the scrollPosition:

func scrollViewDidScroll(scrollView: UIScrollView) {
   //your Code
}

---

或者如果你想要单行：

let scrollView = view.subviews.filter { $0 is UIScrollView }.first as! UIScrollView
scrollView.delegate = self

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