Xcode/iOS:如何在向下滚动时隐藏Navigation- AND ToolBar？

Question

我想在我的iPhone上向下滚动两个栏.当我向上滚动时,它们应该再次出现..我该如何处理？

Answer 1

- (void)scrollViewWillBeginScroll :(UIScrollView *)scrollView {
      if (scrollView.contentOffset.y < lastOffset.y) {
                 [toolBar setHidden:YES];
                 [[[self navigationController] navigationBar] setHidden:YES];
      } else{
                 // unhide
      }
}

- (void)scrollViewDidScroll :(UIScrollView *)scrollView {
      /// blah blah
      lastOffset = scrollView.contentOffset;
}

注意:它lastOffset是一个CGPoint,它在你的头文件中:@Interface.

Answer 2

接受的答案对我不起作用，因为它scrollViewWillBeginScroll:不是委托方法。

相反，我这样做

-(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
    [[NSNotificationCenter defaultCenter] postNotificationName:@"BarsShouldHide" object:self];

}

-(void)scrollViewDidEndDragging:(UIScrollView *)scrollView 
                 willDecelerate:(BOOL)decelerate
{
    if(!decelerate)
        [[NSNotificationCenter defaultCenter] postNotificationName:@"BarsShouldUnhide" 
                                                            object:self];
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    [[NSNotificationCenter defaultCenter] postNotificationName:@"BarsShouldUnhide"
                                                        object:self];
}

应用程序对象中的任何位置都可以侦听此通知，例如

- (void)viewDidLoad
{
    [super viewDidLoad];
    [[NSNotificationCenter defaultCenter] addObserverForName:@"BarsShouldHide" 
                                                      object:nil
                                                       queue:nil
                                                  usingBlock:^(NSNotification *note) {
        //hide tab bar with animation;
    }];
    [[NSNotificationCenter defaultCenter] addObserverForName:@"BarsShouldUnhide" 
                                                      object:nil
                                                       queue:nil
                                                  usingBlock:^(NSNotification *note) {
        //Unhide tab bar with animation;
    }];
}

此代码将隐藏任何滚动的栏。如果你只想上下，那么locationOffset与接受的答案中相同的技巧应该有效。