Swift: Help troubleshoot Segue data from one view to another - ios

Question

Hi I am very new to Swift. I have watched several different videos and tutorials on youtube and I am unable to identify what I am doing wrong.
I am trying to take the data from a check-in view and segue it to the summary view. The code runs, and I am able to move through the app, but the data does not move. Below is the code for the two different swift files. Any insight would be greatly appreciated.
Check-In:
import Foundation
import UIKit
class VieNewCheckIN : UIViewController {
#IBOutlet var SWR: UILabel!
#IBOutlet var ModelNumber: UITextField!
#IBOutlet var SerialNumber: UITextField!
#IBOutlet var Notes: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
guard let viewnewsummary = segue.destination as? ViewNewSummary else { return }
viewnewsummary.NotesValue = Notes.text
viewnewsummary.SerialNumberValue = SerialNumber.text
viewnewsummary.ModelNumberValue = ModelNumber.text
}
}
Summary:
import Foundation
import UIKit
class ViewNewSummary : UIViewController {
#IBOutlet var FirstNameLabel: UILabel!
var FirstNameValue : String!
#IBOutlet var LastNameLabel: UILabel!
var LastNameValue : String!
#IBOutlet var IDLabel: UILabel!
var BaylorIDValue : String!
#IBOutlet var EmailLabel: UILabel!
var BaylorEmailValue : String!
#IBOutlet var PhoneNumberLabel: UILabel!
var PhoneNumberValue : String!
#IBOutlet var ModelNumberLabel: UILabel!
var ModelNumberValue : String!
#IBOutlet var SerialNumberLabel: UILabel!
var SerialNumberValue : String!
#IBOutlet var NotesLabel: UILabel!
var NotesValue : String!
override func viewDidLoad() {
super.viewDidLoad()
FirstNameLabel.text = FirstNameValue
LastNameLabel.text = LastNameValue
BaylorIDLabel.text = BaylorIDValue
BaylorEmailLabel.text = BaylorEmailValue
PhoneNumberLabel.text = PhoneNumberValue
ModelNumberLabel.text = ModelNumberValue
SerialNumberLabel.text = SerialNumberValue
NotesLabel.text = NotesValue
}
}

Answer 1

Verify prepare(for:sender:) is called, e.g. using breakpoints or print/caveman debugging;
verify ViewNewSummary.viewDidLoad() is called, too;
verify prepare is called before viewDidLoad.
My suspicion is that viewDidLoad is called before prepare(for:sender:) is called; that'd make sense since you need an initialized view controller object to prepare the segue with.
So you will want to add viewWillAppear(_:) as a quick fix:
extension ViewNewSummary {
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
FirstNameLabel.text = FirstNameValue
LastNameLabel.text = LastNameValue
BaylorIDLabel.text = BaylorIDValue
BaylorEmailLabel.text = BaylorEmailValue
PhoneNumberLabel.text = PhoneNumberValue
ModelNumberLabel.text = ModelNumberValue
SerialNumberLabel.text = SerialNumberValue
NotesLabel.text = NotesValue
}
}
If that doesn't scale well for all cases, you may want to look into property observers, like
var PhoneNumberValue : String! {
didSet {
guard isViewLoaded else { return }
PhoneNumberLabel.text = PhoneNumberValue
}
}