title: UIPickerView width constraint issue
body: <p>I need to add UIPickerView to UIAlertController. I use code:</p>
  
  <pre><code>let alertView = UIAlertController()
  let pickerView = UIPickerView()
  pickerView.translatesAutoresizingMaskIntoConstraints = false
  
  alertView.view.addSubview(pickerView)
  pickerView.topAnchor.constraint(equalTo: alertView.view.topAnchor, constant: 50).isActive = true
  pickerView.bottomAnchor.constraint(equalTo: alertView.view.bottomAnchor, constant: -50).isActive = true
  pickerView.centerXAnchor.constraint(equalTo: alertView.view.centerXAnchor).isActive = true
  pickerView.widthAnchor.constraint(equalTo: alertView.view.widthAnchor).isActive = true
  
  present(alertView, animated: true)
  </code></pre>
  
  <p>Here it is a result:</p>
  
  <p><a href="https://i.stack.imgur.com/Rn2GR.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Rn2GR.png" alt="enter image description here"></a></p>
  
  <p>Why width of the UIPickerView more than UIAlertController?</p>
  
  <p>Also I tried:</p>
  
  <pre><code>pickerView.widthAnchor.constraint(equalTo: alertView.view.widthAnchor, multiplier: 0.5).isActive = true
  </code></pre>
  
  <p>But got the same result...</p>