showNavBarAnimated doesn't animate constraints.

[markst]

When calling hideNavbarAnimated: & showNavBarAnimated: combined with scrollable view constraints, the constraints are not animated properly.

The reason for this is the setNeedsLayout method within the animation block. The correct way to animate constraints is to call layoutIfNeeded within an animation block.

See "Animating Changes Made by Auto Layout": https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/AutolayoutPG/AutoLayoutbyExample/AutoLayoutbyExample.html

The following resolves animation issues for me:

- (void)showNavBarAnimated:(BOOL)animated
{
    if (self.scrollableView != nil) {
        BOOL isTracking = self.panGesture.state == UIGestureRecognizerStateBegan || self.panGesture.state == UIGestureRecognizerStateChanged;
        if (self.collapsed || isTracking) {
            self.panGesture.enabled = NO;
            if (!self.scrollableViewConstraint) {
                // Frame version
                CGRect rect = [self scrollView].frame;
                rect.origin.y = 0;
                [self scrollView].frame = rect;
            }
            [UIView animateWithDuration:animated ? 0.1 : 0 animations:^{
                self.scrollableHeaderConstraint.constant = 0;
                self.lastContentOffset = 0;
                self.delayDistance = -self.navbarHeight;
                [self scrollWithDelta:-self.navbarHeight];
                [self.view layoutIfNeeded];
            } completion:^(BOOL finished) {
                self.panGesture.enabled = YES;
            }];
        } else {
            [self updateNavbarAlpha:self.navbarHeight];
        }
    }
}

[andreamazz]

Hi @markst You're right, that was a brain fart on my part, I'll fix it right away. thanks for the heads up

[markst]

No worries. Thanks for creating this. I think layoutIfNeeded needs to be set on other animation blocks too.