Application frame leaves blank line at the top

Question

Any clues why my programmatically defined UIScrollView (using the application frame) always leaves an empty space at the top (below the navigationBar) of 20 pixels. How can I close that?

UIScrollView *vScrollView = [[UIScrollView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];
vScrollView.backgroundColor = [UIColor redColor];

My screen looks like this:

• status bar
• -- Navigation bar
• --- the mysterious gap (10px?)
• ---- my Scrollviewcontent (with red background color)

How do I need to call the application frame size to avoid that gap?

Answer 1

What does your application tells in info.plist file about using status bar? Is it enabled or disabled? If I understand correctly, you look at status bar's 20 pixels.

Answer 2

Are you hiding the status bar in your app delegate?

- (void) applicationDidFinishLaunching:(UIApplication *)application {
    [application setStatusBarHidden:YES];
    ...
}

Answer 3

I found I use the wrong frame coordinates "applicationFrame". All works fine when changing it to the bounds.

UIScrollView *vScrollView = [[UIScrollView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

Answer 4

UIScreen-applicationFrame is the full screen rectangle with the status bar (clock) removed. Since your scroll view is inside the view area of the navigation controller, you need to use coordinates in the inner view's coordinate space.

Even using UIScreen-bounds isn't giving you quite the right result since that rect would be the full size of the screen including the space that should be taken by the navigation bars. Using -bounds, you'll find your UIScrollView actually runs 64 pixels off the bottom of the screen.

Assuming you're creating the scroll view in the UINavigationController's -loadView method, something like this should work:

- (void)loadView {
  [super loadView];
  UIScrollView *sv = [[UIScrollView alloc] initWithFrame:self.view.bounds];
  [self.view addSubview:sv];
  [sv release];
}