如何在iOS 7中将UINavigationBar的高度从64点更改为44点？

Question

In iOS 7, the height of a UINavigationBar within a UINavigationController is extended to 64 points such that it can underlap the status bar. How can I change the height to 44 points?

Here's what it looks like currently:

Answer 1

In other words: how can I prevent the UINavigationBar from underlapping the status bar?

As noted in this blog post by Jared Sinclair (see point #4):

UINavigationController will alter the height of its UINavigationBar to either 44 points or 64 points, depending on a rather strange and undocumented set of constraints. If the UINavigationController detects that the top of its view's frame is visually contiguous with its UIWindow's top, then it draws its navigation bar with a height of 64 points. If its view's top is not contiguous with the UIWindow's top (even if off by only one point), then it draws its navigation bar in the “traditional” way with a height of 44 points. This logic is performed by UINavigationController even if it is several children down inside the view controller hierarchy of your application. There is no way to prevent this behavior.

Using Auto Layout, I was able to get a height of 44 points on my UINavigationController 's UINavigationBar by initially setting the frame of UINavigationController 's view such that it doesn't line up with the window's top. Here's some example code:

- (void)viewDidLoad {

    UIViewController *viewController = [[UIViewController alloc] init];
    viewController.view.backgroundColor = [UIColor whiteColor];

    UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:viewController];
    navigationController.view.frameHeight = [UIApplication sharedApplication].keyWindow.frameHeight - 20;
    navigationController.view.frameY = 20;

    [self addnavigationController:navigationController];
    [self.view addSubview:navigationController.view];
    [navigationController didMoveToParentViewController:self];

    // Set the frame initially so that the top of the UINavigationController's view doesn't line up with the top of the UIWindow's view
    navigationController.view.frame = (CGRect) {
        .origin.x = navigationController.view.frame.origin.x,
        .origin.y = 20,
        .size.width = navigationController.view.frame.size.width,
        .size.height = [UIApplication sharedApplication].keyWindow.frameHeight - 20
    };
}

- (void)updateViewConstraints
{
    // Set your actual constraints here
}

Here's what the result looks like (notice how the UINavigationBar 's height is 44 points):