Elements in View Controller Disappear When Clicking or Tapping Them - ios

Question

I am developing an app on XCode using Swift 2 and have run into an error with my UI. I have placed a UILabel, UITextView, and UITextField on the View Controller of interest.
Before inputting the UITextField, everything worked fine. I inserted the text field and assigned the proper constraints and when simulating the app, clicking on the text field will cause all of the UI elements to disappear or the alpha to go instantaneously to zero (I'm not sure which of the two is actually happening).
I'm not receiving any feedback via the console and the app itself does not crash.
Here is my code:
//Declare the following UI objects to be manipulated
#IBOutlet weak var labelOneTitle: UILabel!
#IBOutlet weak var textDescription: UITextView!
#IBOutlet weak var fieldInput: UITextField!
override func viewDidLayoutSubviews() {
//Set UI object alphas to zero prior to loading the view
labelOneTitle.alpha = 0
textDescription.alpha = 0
fieldInput.alpha = 0
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
override func viewDidAppear(animated: Bool) {
UIView.animateWithDuration(2) { () -> Void in
self.labelOneTitle.alpha = 1
}
UIView.animateWithDuration(3) { () -> Void in
self.textDescription.alpha = 1
}
UIView.animateWithDuration(3) { () -> Void in
self.fieldInput.alpha = 1
}
}

Answer 1

It might be the UIViewController.viewDidLayoutSubviews rechecking all the constraints and reconfiguring the view as per the the class reference:
When the bounds change for a view controller's view, the view adjusts the positions of its subviews and then the system calls this method. However, this method being called does not indicate that the individual layouts of the view's subviews have been adjusted. Each subview is responsible for adjusting its own layout.
Your view controller can override this method to make changes after
the view lays out its subviews. The default implementation of this
method does nothing.
When you click on the UITextField the keyboard appears (Probably) and thus recalling the method to set the alpha of all your UI Elements to 0.
If you'd move setting the alpha's to 0 to the viewDidLoad() than the problem might go away.