淡入淡出/向上滚动显示UIButton

Question

我有一个tableView。在视图上是UIButton。我希望当向下滚动按钮淡入淡出，当滚动停止或向上按钮显示。

代码：

- (void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView{ 
NSLog(@"Start scroll"); 

//I assume the buttons are within your cells so you will have to enable them within your cells so you will probably have to handle this by sending a custom message to your cells or accessing them with properties. 
CGRect frame = addCommentBtn.frame; 
frame.origin.y = scrollView.contentOffset.y + self.newsTableView.frame.size.height + 4; 
addCommentBtn.frame = frame; 

[self.view bringSubviewToFront:addCommentBtn];} 

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{ 
NSLog(@"End scroll"); 

// do the same to enable them back 
CGRect frame = addCommentBtn.frame; 
frame.origin.y = scrollView.contentOffset.y + self.newsTableView.frame.size.height + 4; 
addCommentBtn.frame = frame; 

[self.view bringSubviewToFront:addCommentBtn];} 

，但无法正常工作！ 谢谢

Answer 1

您正在使用错误的方法。而不是 scrollViewWillBeginDecelerating:使用scrollViewDidScroll:并更新按钮alpha和位置基于滚动视图的contentOffset。