Showing/hiding navigation bar with smooth animation

Question

I have a navigation based app. The first view (rootcontroller) starts with three large buttons only. No navigationbar. From there, everything else is tableviews and have

Answer 1

You can customize the navigation bar animation and duration by the following methods. It will provide you callback once animation will be completed.

   // pass a param to describe the state change, an animated flag and a completion block matching UIView animations completion
    - (void)setNavigationBarVisible:(BOOL)visible animated:(BOOL)animated completion:(void (^)(BOOL))completion {

        // fail if the current state matches the desired state
        if ([self navigationBarIsVisible] == visible) return completion(YES);

        // get a frame calculation ready
        CGFloat nheight = self.navigationController.navigationBar.frame.size.height;
        CGFloat noffsetY = (visible)? -nheight : nheight;

        // zero duration means no animation
        CGFloat duration = (animated)? 0.3 : 0.0;

        [UIView animateWithDuration:duration animations:^{
            CGRect nframe = self.navigationController.navigationBar.frame;
            self.navigationController.navigationBar.frame = CGRectOffset(nframe, 0, noffsetY);
        } completion:completion];
    }

    // know the current state of the navigation bar
    - (BOOL)navigationBarIsVisible {
        return self.navigationController.navigationBar.frame.origin.y < CGRectGetMinY(self.view.frame);
    }

    // Show or Hide navigation bar
    [self setNavigationBarVisible:![self navigationBarIsVisible] animated:YES completion:^(BOOL finished) {
        NSLog(@"navigation bar finished");
    }];

Before hide a Navigation bar:

After hide a Navigation bar: