How to set UIScrollView scrolled to bottom? - swift

Question

I want my scroll view (which is in top half of view) to be scrolled to the bottom of the scroll view when my app is booted up. I want it so that when the app boots up I cannot scroll down any further.
I have tried:
scrollView.contentSize = CGSize(width: self.view.frame.size.width, height: 667)
scrollView.contentOffset = CGPoint(x:0, y:self.view.frame.size.height )
However, this only brings my scroll view almost to the bottom. I can still scroll down a little, which I don't want.
I have also tried:
let bottomOffset = CGPoint(x: 0, y: scrollView.contentSize.height - scrollView.bounds.size.height)
scrollView.setContentOffset(bottomOffset, animated: true)
but that doesn't seem to work either.

Answer 1

You can try below code for moving scroll view to the bottom of the screen:
extension UIScrollView {
func scrollToBottom() {
let bottomOffset = CGPoint(x: 0, y: contentSize.height - bounds.size.height + contentInset.bottom)
setContentOffset(bottomOffset, animated: true)
}
}
Add this extension and try below code to access this extension for scroll to the bottom:
scrlView.scrollToBottom()
If it is not working properly then you can also try to execute in mail queue:
DispatchQueue.main.async {
scrlView.scrollToBottom()
}
Let me know if you face any problem.

Answer 2

You can use this extension if you like :
extension UIScrollView {
func scrollToBottom(animated: Bool) {
if self.contentSize.height < self.bounds.size.height { return }
let bottomOffset = CGPoint(x: 0, y: self.contentSize.height - self.bounds.size.height)
self.setContentOffset(bottomOffset, animated: animated)
}
}
But i would suggest you to not use this as the code is little harder to maintain . What i would suggest is that use a TableView or Collection View inside your View Controller and do the following :
Invert your TableView or CollectionView using the below code . This will make the top the TableView or CollectionView go to bottom but the cell will be inversed:
yourTableView.transform = CGAffineTransform(scaleX: 1, y: -1)
Then in invert your cells using the same code.
cell.transform = CGAffineTransform(scaleX: 1, y: -1)
So by default properties of ios , the tableview should begin from the top . Since we transformed it to show up in bottom of view , the content will be there.

Answer 3

Here is the NSScrollView equivalent to the UIScrollView Extension above.
extension NSScrollView {
func scrollToBottom() {
let variableHeight = self.contentView.documentRect.height
let fixedHeight = self.contentSize.height
if (variableHeight > fixedHeight) {
self.contentView.scroll(to: CGPoint(x: 0, y: variableHeight))
}
}
}