Show/Hide chrome in UINavigationViewController on iOS 7

gistfile1.m

@property (nonatomic, assign, getter = isChromeHidden) BOOL chromeHidden;

- (BOOL)prefersStatusBarHidden {
    return self.isChromeHidden;
}

- (UIStatusBarAnimation)preferredStatusBarUpdateAnimation {
    return UIStatusBarAnimationSlide;
}

- (void)syncStatusBarWithDuration:(CGFloat)duration {
    BOOL hideStatusBar = [self prefersStatusBarHidden];
    [UIView animateWithDuration:(26.0 * duration / 64.0)
                          delay:(hideStatusBar ? 0.0 : 37.0 * duration / 64.0)
                        options:UIViewAnimationOptionBeginFromCurrentState | (hideStatusBar ? UIViewAnimationOptionCurveEaseIn : UIViewAnimationOptionCurveEaseOut)
                     animations:^{
                         [self setNeedsStatusBarAppearanceUpdate];
                     }
                     completion:nil
     ];
}

- (void)setChromeHidden:(BOOL)hidden {
    if (_chromeHidden != hidden) {
        _chromeHidden = hidden;
        [self syncStatusBarWithDuration:UINavigationControllerHideShowBarDuration];
        [self.navigationController setToolbarHidden:hidden animated:YES];
        [self.navigationController setNavigationBarHidden:hidden animated:YES];
    }
}

- (void)toggleChrome {
    [self setChromeHidden:!self.isChromeHidden];
}