ios - 向下/向上滚动时淡出/显示 UIButton

Question

我有一个 TableView 。 View 中是 UIButton。我想要什么时候向下滚动按钮淡出以及什么时候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

您使用了错误的方法。代替scrollViewWillBeginDecelerating: 使用 scrollViewDidScroll: 并根据 ScrollView 的 contentOffset 更新按钮 alpha 和位置。