How does Twitter official iOS app changes status bar with custom text

Question

The new official Twitter for iOS app changes statusbar just like in the picture above. How to implement such a feature?

[image source]

Answer 1

Here's how I do it in my app with a rotating animation:

-(void)showStatusBarMessage:(NSString *)message hideAfter:(NSTimeInterval)delay
{
    __block UIWindow *statusWindow = [[UIWindow alloc] initWithFrame:[UIApplication sharedApplication].statusBarFrame];
    statusWindow.windowLevel = UIWindowLevelStatusBar + 1;
    UILabel *label = [[UILabel alloc] initWithFrame:statusWindow.bounds];
    label.textAlignment = UITextAlignmentCenter;
    label.backgroundColor = [UIColor blackColor];
    label.textColor = [UIColor grayColor];
    label.font = [UIFont boldSystemFontOfSize:13];
    label.text = message;
    [statusWindow addSubview:label];
    [statusWindow makeKeyAndVisible];
    label.layer.transform = CATransform3DMakeRotation(M_PI * 0.5, 1, 0, 0);
    [UIView animateWithDuration:0.7 animations:^{
        label.layer.transform = CATransform3DIdentity;
    }completion:^(BOOL finished){
        double delayInSeconds = delay;
        dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
        dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
            [UIView animateWithDuration:0.5 animations:^{
                label.layer.transform = CATransform3DMakeRotation(M_PI * 0.5, -1, 0, 0);
            }completion:^(BOOL finished){
                statusWindow = nil;
                [[[UIApplication sharedApplication].delegate window] makeKeyAndVisible];
            }];
        });
    }];
}

I have it in a category on UIViewController to use it from whatever controller in the app.

EDIT: Needs QuartzCore.framework to be referenced and #import <QuartzCore/QuartzCore.h> to be added.