Ios 向下/向上滚动时的淡入/显示按钮

我有一个桌面视图。“打开视图”按钮。我想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：

但是不能正常工作！

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谢谢

您使用了错误的方法。而不是

ScrollViewWillBeginDelegrating:

使用

scrollViewDidScroll:

并根据滚动视图的

contentOffset

更新按钮alpha和位置

- (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];}