Presenting a popup view controller programatically using auto layout - ios

Question

I am building my UI from code and need to present another view controller as a popover, over the current controller. The popover will act as a modal dialog and will use about 50% of the screen size. The contents of the popover must be constrained in the screen center and support device rotation.
My initial implementation was done in viewDidLoad() of the PopoverController class and it worked as expected. However, I do not want view code in my controllers. After moving the popover view to a separate file, the fun began; auto layout and device rotation no longer worked as expected.
I have made a basic app showcasing this. The main controller has a button for displaying the popover. The popover has yellow background and should display a blue view in the center.
MainViewController :: Test button for displaying the popover
#objc func boxButtonTapped() {
let vc = PopoverController()
vc.modalPresentationStyle = .overCurrentContext
vc.modalTransitionStyle = .crossDissolve
present(vc, animated: true, completion: nil)
}
Popover Controller
class PopoverController: UIViewController {
var popoverView = PopoverView()
override func viewDidLoad() {
super.viewDidLoad()
}
override func loadView() {
view = popoverView
}
}
Popover View
class PopoverView: UIView {
let blueBox: UIView = {
let bb = UIView()
bb.backgroundColor = .blue
//bb.frame.size = CGSize(width: 100, height: 100)
bb.translatesAutoresizingMaskIntoConstraints = false
return bb
}()
override init(frame: CGRect) {
super.init(frame: frame)
createSubViews()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
createSubViews()
}
func createSubViews() {
translatesAutoresizingMaskIntoConstraints = false
backgroundColor = .yellow
addSubview(blueBox)
blueBox.centerXAnchor.constraint(equalTo: self.centerXAnchor).isActive = true
blueBox.centerYAnchor.constraint(equalTo: self.centerYAnchor).isActive = true
blueBox.heightAnchor.constraint(equalTo: self.heightAnchor, multiplier: 0.7).isActive = true
blueBox.widthAnchor.constraint(equalTo: self.widthAnchor, multiplier: 0.4).isActive = true
}
}
When running the above code, the popover doesn`t even display! This is my first question, can anyone see why?
If I change translatesAutoresizingMaskIntoConstraints = false to true. Then the popover displays, but it does not resize when the device rotates. I do not know why and I don´t understand why translatesAutoresizingMaskIntoConstraints needs to be set to true in order for the view to display in the first place.
There must be a simple solution for such a trivial task. I have tried so many different approaches and listing them here would be impossible. I am new to IOS dev and Swift and I really would like to get a good start with clean code. Thank you for your time!
Update
I published the sample project on GitHub. So if you have the time and want a challenge/prove a concept then here it is: https://github.com/igunther/CleanController

Answer 1

If you are not adding constraints yourself - which, in this case, you are not - you still need to tell the view how to behave.
Change your createSubviews() function to this:
func createSubViews() {
//translatesAutoresizingMaskIntoConstraints = false
autoresizingMask = [.flexibleHeight, .flexibleWidth]
backgroundColor = .yellow
addSubview(blueBox)
blueBox.centerXAnchor.constraint(equalTo: self.centerXAnchor).isActive = true
blueBox.centerYAnchor.constraint(equalTo: self.centerYAnchor).isActive = true
blueBox.heightAnchor.constraint(equalTo: self.heightAnchor, multiplier: 0.7).isActive = true
blueBox.widthAnchor.constraint(equalTo: self.widthAnchor, multiplier: 0.4).isActive = true
}
That will allow auto-layout to re-layout your view(s) on device rotation.

Answer 2

According to Apple docs for translatesAutoresizingMaskIntoCon
If this property’s value is true, the system creates a set of constraints that duplicate the behavior specified by the view’s autoresizing mask.
and
By default, the property is set to true for any view you programmatically create. If you add views in Interface Builder, the system automatically sets this property to false.
My guess is that when set to false it's looking for constraints that don't exist.
As far as the rotation goes, you could put shouldAutorotate property in your VC?