检测UIScrollview底部到达 [英] Detect UIScrollview bottom reached

问题描述

我有一个带图像的UIScrollView，当用户滚动到scrollview的末尾时，我想更新内容。这是我的代码，用于检测何时到达滚动视图的底部：

I have a UIScrollView with images and when the user scrolls to the end of the scrollview i want to update the content. This is my code to detect when the bottom of the scrollview is reached:

以下代码在中实现scrollViewDidScroll：委托

CGFloat scrollViewHeight = imagesScrollView.bounds.size.height;
CGFloat scrollContentSizeHeight = imagesScrollView.contentSize.height;
CGFloat bottomInset = imagesScrollView.contentInset.bottom;
CGFloat scrollViewBottomOffset = scrollContentSizeHeight + bottomInset - scrollViewHeight;

if(imagesScrollView.contentOffset.y > scrollViewBottomOffset){


    [imagesView addSubview:imagesBottomLoadingView];

    [self downloadImages];

}

我的问题是，当用户滚动到底部时，我的函数被多次调用，但我想只调用一次。我尝试使用imagesScrollView.contentOffset.y == scrollViewBottomOffset但是它不起作用并且没有调用该函数

My problem is that when the user scrolls to bottom, my function is called several times, but i want to call it only once. I tried with imagesScrollView.contentOffset.y == scrollViewBottomOffset but it doesn't work and the function is not called

推荐答案

你有没有想到添加一个布尔值。第一次调用方法时可能会更新它，也可能在用户向上滚动时更新它。

Have you thought of adding a boolean. update it when the method is called for the first time and maybe when user scrolls back up.

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