将“收藏夹”视图滚动到顶部

Question

I have a following collection view. When the user scrolls the view up, I want the collection view to go all the way up. Similarly, when it is scrolled down, I want it to come back to its original position.

I have a uiview and imageView above the collectionview.

Now, If this was a tableview, I would have used header. How do i achieve this behavious. I am out of Ideas.

Thanks in advance

Answer 1

UICollectionView is the sub-class of UIScrollView so you can achieve what you want is just by the scrollview delegate method and the constraints of your UIView and UIImageView upon the UICollectionView.

Here I am going to give you one example to achieve this with scrollview delegate.

func scrollViewDidScroll(_ scrollView: UIScrollView) {
        if scrollView == collectionView{
            if scrollView.contentOffset.y == 0{
                UIView.animate(withDuration: 0.5) { () -> Void in
                    self.constTopTagHeight.constant = 175 // Your UIView and imageview constraints adjust.  
                    self.view.layoutIfNeeded()
                }
            }
            else{
                UIView.animate(withDuration: 0.5) { () -> Void in
                    self.constTopTagHeight.constant = 0 // Your UIView and imageview constraints adjust.
                    self.view.layoutIfNeeded()
                }
            }
        }
    }

Hope this help you.