Xcode/iOS: How to hide Navigation- AND ToolBar on scroll down?

Question

I would like to hide both bars on scroll down on my iPhone. When I scroll up, they should appear again.. How can I handle this?

Answer 1

The accepted answer does not work for me, as scrollViewWillBeginScroll: is not a delegate method.

Instead I do

-(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];
}

Anywhere in the app objects can listen for this notification,like

- (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;
    }];
}

This code will hide the bars for any scroll. if you want to have only on down, the same locationOffset trick as in the accepted answer should work.

Answer 2

- (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;
}

Note : lastOffset is an CGPoint and it goes in your header file: @Interface.

Answer 3

Here's my solution in Swift; it works beautifully

func scrollViewDidScroll(scrollView: UIScrollView) {
    let navController: UINavigationController = self.navigationController!
    if self.collectionView.panGestureRecognizer.translationInView(self.view).y <= 0.0 {
        defaultCenter.postNotificationName("stuffShouldHide", object: self)
    } else {
        defaultCenter.postNotificationName("stuffShouldUnhide", object: self)
    }
}

Answer 4

You might check this, available from iOS8, i think this is the reverse of what you are looking for...but worth checking as it is something standard and this is how Safari works.

Swift

var hidesBarsOnSwipe: Bool

Objective-C

@property(nonatomic, readwrite, assign) BOOL hidesBarsOnSwipe Discussion

When this property is set to YES, an upward swipe hides the navigation bar and toolbar. A downward swipe shows both bars again. If the toolbar does not have any items, it remains visible even after a swipe. The default value of this property is NO.