What is causing NSNull length unrecognized selector keyCommand error

Question

I have this class/storyboard scene in a project that up to last night worked fine for the past 4 weeks i worked on it.

I have managed to comment out practically everything and I still get the crash when tapping on the UITextField and typing a number. It only crashes when I type in a value, otherwise it doesn't crash.

Here is the class as I am running it now:

import Foundation
import UIKit
import HealthKit
import CoreData

class WorkoutViewController: UITableViewController {

//Properties
    @IBOutlet var numberOfLapsTextField: UITextField?
    @IBOutlet var metersPerLapTextField: UITextField?
    @IBOutlet var workoutDurationTextField: UITextField?
    @IBOutlet var paceTextField: UITextField?

    var  healthStore:HKHealthStore?

override func viewDidLoad() {
        super.viewDidLoad()
}

Originally it had the IBOutlets as ! instead of ? And it has a CoreData stack property, some blurred background effects for the tableview background, fetches user's weight from health store on viewDidLoad, a predicate helper method for health store fetches and a cancel and done button. The done button captured data from the textfields, made some computations and saved data to the health store and to coredata. But ALL of this has been commented out leaving only what is seen above.

I did managed to get a weird stack trace in the console one time (can't seem to get it anymore) that read:

[UIPhysicalKeyboardEvent _matchesKeyCommand:]

and a few others like it just before it.

Im stumped, any ideas? Exception breakpoints is one but it just throws me to the AppDelegate class declaration line where UIResponder is adopted. Ive learned and rebuilt. I don't know what else to look for.

Im thinking its a corrupt storyboard file because Ive added and removed scenes with textfields and they all behave the same. Here is my storyboard.xml file:

http://www.santiapps.com/iOS/Main.storyboard.xml

Answer 1

Ok I deleted the navigation controllers and tab bar controller and re-added them, and the problem is gone! There are no more crashes when I type in data. It was obviously a corrupted scene but the weird thing is that all of a sudden, all scenes with uitextfields got corrupted in the same way.