UIView programatic constraints not working - ios

Question

As a simple starting point. I'm trying to create a custom button that has an activity indicator in the middle.
After a tap - it will indicate that it's thinking
I'm pretty much stuck at step 1 - adding the indicator to be centred in the surrounding view.
No matter want constraints I try it always appears in the top left corner.
What am I missing?
Here's my playground code.
//: Playground - noun: a place where people can play
import PlaygroundSupport
import UIKit
class ConnectButton : UIView {
fileprivate let activityIndicator: UIActivityIndicatorView = {
let activityIndicator = UIActivityIndicatorView()
activityIndicator.color = #colorLiteral(red: 1, green: 1, blue: 1, alpha: 1)
activityIndicator.hidesWhenStopped = true;
activityIndicator.stopAnimating();
activityIndicator.activityIndicatorViewStyle = .white;
return activityIndicator;
}()
private func initView() {
translatesAutoresizingMaskIntoConstraints = true;
addSubview(activityIndicator);
NSLayoutConstraint.activate([
activityIndicator.centerYAnchor.constraint(equalTo: self.centerYAnchor),
activityIndicator.leftAnchor.constraint(equalTo: self.centerXAnchor)
])
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder);
self.initView();
}
override init(frame: CGRect) {
super.init(frame: frame);
self.initView();
}
public func startAnimating() {
activityIndicator.startAnimating();
}
public func stopAnimating() {
activityIndicator.stopAnimating();
}
}
let dimensions = (width:200, height: 50);
let connectButton = ConnectButton(
frame: CGRect(
x: dimensions.width / 2,
y: dimensions.height / 2,
width: dimensions.width,
height: dimensions.height
)
)
connectButton.startAnimating();
connectButton.backgroundColor = #colorLiteral(red: 0.1764705926, green: 0.4980392158, blue: 0.7568627596, alpha: 1);
PlaygroundPage.current.liveView = connectButton

Answer 1

You want to set translatesAutoresizingMaskIntoConstraints to false onto UIActivityIndicatorView. Otherwise, UIKit will create constraints based on the resizing masks set on the, which will conflict with the ones you already added.
fileprivate let activityIndicator: UIActivityIndicatorView = {
let activityIndicator = UIActivityIndicatorView()
activityIndicator.color = #colorLiteral(red: 1, green: 1, blue: 1, alpha: 1)
activityIndicator.hidesWhenStopped = true
activityIndicator.stopAnimating()
activityIndicator.activityIndicatorViewStyle = .white
activityIndicator. translatesAutoresizingMaskIntoConstraints = false
return activityIndicator
}()

Answer 2

Another solution: Create your UIActivityIndicator with a given frame from your superView as you already do, and simply call:
activityIndicator.center = self.center
And avoid the NSLayoutConstraints alltogether, unless you really need them for something.
However, as I mentioned in the commentsection, make sure you have your UIView laid out to the correct size before calling above line. Otherwise your result will be exactly the same.