Setting dynamic height on UItextview to fit content programmatically - ios

Question

Just by programmatically coding, I'm trying to achieve something like below image. TextView and ContainerView are embedded in scrollview although it is not shown in the image.
Here is my code for this.
override func viewDidLoad() {
super.viewDidLoad()
let margin = CGFloat(10)
textView = UITextView()
textView.text = "asdadaasdadadadasdadadadasdadadadasdadadadasdadadadasdadadadasdadadadasdadadadasdadadadasdadadadasdadadadasdadadadasdadadadasdadadadasdadadadaadasdadadadasdadadadasdadadadasdadadadasdadadadasdadadadasdadadadasdadadadasdadadadasdadadadasdadadadasdadadadasdadadaddadd"
let contentSize = textView.sizeThatFits(textView.bounds.size)
textView.frame = CGRectMake(margin, 0, self.view.frame.width - 2 * margin, contentSize.height)
let scrollView = UIScrollView(frame: CGRect(x: 0, y: 0, width: self.view.frame.width, height: self.view.frame.height - 50))
let containerView = UIView(frame: CGRectMake(margin, contentSize.height + margin, self.view.frame.width - 2 * margin, self.view.frame.height))
let button1 = UIButton(frame: CGRectMake(margin, contentSize.height + containerView.frame.height + 2 * margin, (view.frame.width - 2 * margin)/2, 30))
scrollView.contentSize = CGSize(width: self.view.frame.width, height: button1.frame.origin.y + button1.frame.height + margin)
self.view.addSubview(scrollView)
scrollView.addSubview(textView)
scrollView.addSubview(containerView)
scrollView.backgroundColor = UIColor.blueColor()
containerView.backgroundColor = UIColor.yellowColor()
textView.backgroundColor = UIColor.greenColor()
}
The problem is that textview's height is not dynamic to show all content in textview.
I've confirmed that if I add below code in viewdidappear, it does make the height of textview dynamic but it is stacked under Container view because below code runs after ViewDidLoad configured everything.
let contentSize = textView.sizeThatFits(textView.bounds.size)
textView.frame = CGRectMake(margin, 0, self.view.frame.width - 2 * margin, contentSize.height)
What would be the best approach for this kind of problem?
I think this is caused due to rendering order in viewdidload but I'm not 100% sure. It would be great if someone can talk about rendering order too.

Answer 1

To answer the original question, your call to sizeThatFits has no idea how tall the TextView should be because it has no idea how wide you want it to be. I think before the sizeThatFits line you want the following:
textView.frame.size.width = self.view.frame.width - 2 * margin