检查 UIScrollView 是否到达顶部或底部

问题描述

有没有办法知道 UIScrollView 是到达顶部还是底部?可能在方法中:

Is there a way to know if a UIScrollView has reached the top or bottom? Possibly in the method:

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView 
                  willDecelerate:(BOOL)decelerate

推荐答案

在你的类中实现UIScrollViewDelegate，然后添加:

Implement the UIScrollViewDelegate in your class, and then add this:

-(void)scrollViewDidScroll: (UIScrollView*)scrollView
{
    float scrollViewHeight = scrollView.frame.size.height;
    float scrollContentSizeHeight = scrollView.contentSize.height;
    float scrollOffset = scrollView.contentOffset.y;

    if (scrollOffset == 0)
    {
        // then we are at the top
    }
    else if (scrollOffset + scrollViewHeight == scrollContentSizeHeight)
    {
        // then we are at the end
    }
}

希望这就是你所追求的！否则，通过在上面的代码中添加更多条件和 NSLog 滚动偏移的值来进行修补.

Hope this is what you are after! Else have a tinker by adding more conditions to the above code and NSLog the value of scrollOffset.