iOS 7 override the status bar style for a UIViewController. You can also call the setNeedsStatusBarAppearanceUpdate method on the view controller to force the methods to be called again.

iOS7StatusBarStyle

@implementation MyViewController

- (UIStatusBarStyle)preferredStatusBarStyle {
    return UIStatusBarStyleDefault;
}

- (BOOL) prefersStatusBarHidden {
    return NO;
}

- (IBAction) hidStatusBar {
    [UIView animateWithDuration:0.5 animations:^{
        [self setNeedsStatusBarAppearanceUpdate];    
    }];
}

- (UIStatusBarAnimation)preferredStatusBarUpdateAnimation {
    return UIStatusBarAnimationSlide;
}

@end