How to fade out the status bar while not hiding it

问题:

iOS Developers will surely knows about the issue about status bar and the famous "slide/hamburger/drawer". The issue is well explained here: http://uxmag.com/articles/adapting-ui-to-ios-7-the-side-menu

I'm using MMDrawerController library and it has a nice hack that lets us to create a dummy status bar just above the container view controller. Unfortunately this doesn't work really good. What's the news? The news is that I stumbled upon an app (Tinder) that perfectly solve this mind blowing issue. I've created a gif that perfectly shows what Tinder does.

You need to wait a few seconds for seeing the gif because there's a bug in it and I don't know how to get rid of. Just wait one/two seconds and you will able to see the gif correctly.

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Anyway, what Tinder does? When the user taps on the top left menu button and begin to swipe right the status bar fades out neatly. And when the view is revert to the original position the status bar will show up again.

I am both happy and a bit sad for this because this means that a way must be to do it but I really don't know how to implement it (perhaps hacking MMDrawerController). Any help will be so much appreciated.

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IMPORTANT

Please pay attention to the fact that the method setStatusBarHidden: will completely hide the status bar, this means that the entire view is with a height -20px. This is obviously not the solution because as you can see from the gif the view is not stretched.

回答1:

Your main problem is with MMDrawerController. If you'll digg into it you'll find a lot of methods statusbar related such as setShowsStatusBarBackgroundView setStatusBarViewBackgroundColor and more. Something in their code pushes the view up when the statusbar is hidden.

Alternatively you can use another drawer controller or use custom code.

Here's a simple way how to accomplishe this:

ViewControllerA:

-(BOOL)prefersStatusBarHidden
{
    return _hidden;
}
- (void)statusHide
{
    [UIView animateWithDuration:0.4 animations:^() {[self setNeedsStatusBarAppearanceUpdate];
    }completion:^(BOOL finished){}];
}

ViewControllerB: (Container in ViewControllerA)

- (IBAction)move:(UIButton *)sender
{
    parent = (ViewController*)self.parentViewController;
    parent.hidden = !parent.hidden;
    CGRect frame = parent.blueContainer.frame;
    if(parent.hidden)
    {
        frame.origin.x = 150;
    }
    else
    {
        frame.origin.x = 0;
    }

    [UIView animateWithDuration:1 animations:^() {parent.blueContainer.frame = frame;}completion:^(BOOL finished){}];
    [parent statusHide];
}

For iOS 6 compatieblty use:

[[UIApplication sharedApplication] setStatusBarHidden:_hidden withAnimation:UIStatusBarAnimationFade];

The table view and other subviews will stay in their location and won't be pushed up.

Edit:

Adding a NavigationBar:

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.

Taken from here

You could very simply subclass UINavigationController and create your own navbar to avoid this annoyness.

回答2:

i don't know if it will sove your problem but i got almost the same effect using the SWRevealViewController project. In the appDelegate I've set the delegate method from this class to do this:

- (void)revealController:(SWRevealViewController *)revealController willMoveToPosition:(FrontViewPosition)position {
#ifdef DEBUG
    NSArray *teste = @[@"FrontViewPositionLeftSideMostRemoved",@"FrontViewPositionLeftSideMost",@"FrontViewPositionLeftSide",@"FrontViewPositionLeft",@"FrontViewPositionRight",@"FrontViewPositionRightMost",@"FrontViewPositionRightMostRemoved"];
    NSLog(@"%@ %d", teste[position], position);
#endif
    if (position == FrontViewPositionRight)
        [[UIApplication sharedApplication] setStatusBarHidden:YES  withAnimation:UIStatusBarAnimationFade];
    UINavigationController *frontViewController = (id)revealController.frontViewController;
    frontViewController.navigationBar.centerY += (position == FrontViewPositionRight) ?  20 : 0; //  20 == statusbar heihgt
}

- (void)revealController:(SWRevealViewController *)revealController didMoveToPosition:(FrontViewPosition)position {
    if (position == FrontViewPositionLeft)
        [[UIApplication sharedApplication] setStatusBarHidden:NO  withAnimation:UIStatusBarAnimationFade];
}

centerY is a category in the UIView which sets the center.y without dealing the boring part of setting frame variables.

回答3:

Here is how you should do that in iOS 7:

@implementation ViewController
{
    BOOL _hideStatusBar;
}

-(UIStatusBarStyle)preferredStatusBarStyle
{
    return UIStatusBarStyleDefault;
}

-(UIStatusBarAnimation)preferredStatusBarUpdateAnimation
{
    return UIStatusBarAnimationFade;
}

-(BOOL)prefersStatusBarHidden
{
    return _hideStatusBar;
}

-(void)setStatusBarHidden:(BOOL)hidden
{
    [UIView animateWithDuration:1.0 animations:^{
        _hideStatusBar = hidden;
        [self setNeedsStatusBarAppearanceUpdate];
    }];
}

@end

回答4:

Check out the method setStatusBarHidden:withAnimation: on UIApplication. It will allow you to show or hide the status bar and the animation can be none, fade, or slide. You just need to add a call to hide the bar and one to show the bar at the correct times and decide if you like the fade as you illustrated or if the slide works better for you.

https://developer.apple.com/library/ios/DOCUMENTATION/UIKit/Reference/UIApplication_Class/Reference/Reference.html#//apple_ref/occ/instm/UIApplication/setStatusBarHidden:withAnimation:

回答5:

You can used -setStatusBarHidden:withAnimation: if you adjust your views frame in -viewDidAppear:, then you will not see any stretch. Note that autolayout is disabled.

-(void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    CGRect frame = self.view.frame;
    // adjust root view frame 
    frame.origin.y -= 20;
    frame.size.height += 20;

    [self.view setFrame:frame];

    // adjust subviews y position
    for (UIView *subview in [self.view subviews])
    {
        CGRect frame = subview.frame;
        frame.origin.y += 20;
        [subview setFrame:frame];
    }
}

- (IBAction)sliderChanged:(id)sender
{
    UISlider *s = (UISlider *)sender;
    if (s.value > .5)
    {
        UIApplication *app = [UIApplication sharedApplication];
        if (![app isStatusBarHidden])
            [app setStatusBarHidden:YES withAnimation:UIStatusBarAnimationFade];
    }
    else
    {
        UIApplication *app = [UIApplication sharedApplication];
        if ([app isStatusBarHidden])
            [app setStatusBarHidden:NO withAnimation:UIStatusBarAnimationFade];
    }
}