Keep UIScrollView scrolled to bottom

Question

I need somehow to keep scrollview always scrolled to bottom while its height decreases.

It's hard to solve while bounds change animated. Is there some "gravity"-property for purpose like that?

Answer 1

You can achieve this behaviour by using a non-animated version of setContentOffset within the same animation block you use for resizing the UIScrollView — in this case both changes will be animated simultaneously. Something like:

UIView.animateWithDuration(0.5, animations: { () -> Void in

    let delta: CGFloat = 100

    /// Change UIScrollView's height with some delta value, for instance:
    self.scrollView.frame.size.height -= delta

    /// Update content offset with the same delta value:
    self.scrollView.contentOffset.y += delta
})

Answer 2

每次缩小UIScrollView的框架时，尝试使用setContentOffset:animated:滚动到底部。

Answer 3

You are decreasing the height of scrollview with animation. You can use setContentOffset:animated: in the animation completion block. It will keep the scrollview always scrolled to bottom.