How can I detect when iOS ScrollView is at the very top?

Question

How can I detect when the user scrolled to the very top of my collectionView?

I tried to use this code:

func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
   if collectionView.contentOffset.y <= collectionView.contentSize.height - collectionView.frame.size.height {
       print("top")
   }
}

But it prints "top" even if I didn't get to the top.

Answer 1

scrollViewDidEndDragging means the user's finger lifted, but because it has physics to simulate inertia, the view may continue to move. There is another delegate method for exactly what you are looking for: scrollViewDidScrollToTop which as the name implies fires when you get to the top of the scrollview.

EDIT: you can also try:

  func scrollViewDidScroll(_ scrollView: UIScrollView) {
    if scrollView.contentOffset.y <= 0 {
      print("top!")
    }
  }

EDIT third time's the charm? This one only fires once, after the scroll view has stopped moving, if you are at the top.

  override func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
    if scrollView.contentOffset.y == 0 {
      print("top!")
    }
  }