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

Thanks to IOS Rocks and CularBytes for the leads on this. I found two problems (for me) with the above solutions:

1. I always have a container UIView as the only child of my UIScrollView, so I had to update the way I look up the last view in that child UIView (see below)
2. I am offset'ing my content in the UIScrollView and as such needed to calculate the absolute position of that last UIView (so, relative to the window not the parent view)

Also I am using autolayout to pin the sides of the UIScrollView, so I don't need to worry about width (as is CularBytes).

Here's what I came up with and works (in Swift 3.0):

func setScrollViewContentSize() {

    var height: CGFloat
    let lastView = self.myScrollView.subviews[0].subviews.last!
    print(lastView.debugDescription) // should be what you expect

    let lastViewYPos = lastView.convert(lastView.frame.origin, to: nil).y  // this is absolute positioning, not relative
    let lastViewHeight = lastView.frame.size.height

    // sanity check on these
    print(lastViewYPos)
    print(lastViewHeight)

    height = lastViewYPos + lastViewHeight

    print("setting scroll height: \(height)")

    myScrollView.contentSize.height = height
}

I call this in my viewDidAppear() method.