How to set content size of UIScrollView dynamically

Question

I got question about UIScrollview.

The story is I have a UIView named ChartsView which I re-draw it myself by override method drawRec

Answer 1

It is not 100% guaranteed that the last object in scrollView.subviews array will return the highest y-origin object in your scroll view. The subviews array is arranged by Z-Index (i.e the last object in the subviews array will be the object stacked the highest and will be the top-most subview in the scroll view's subviews. Instead it is more accurate to use a basic sort function to iterate through the subviews and get the object with the highest y-origin.

Swift 4

extension UIScrollView {
    func updateContentView() {
        contentSize.height = subviews.sorted(by: { $0.frame.maxY < $1.frame.maxY }).last?.frame.maxY ?? contentSize.height
    }
}

Usage (in viewDidLayoutSubviews or whenever your content size updates):

myScrollView.updateContentView()