Converting to Swift 3 broke custom class encoding/decoding - ios

Question

So I've just converted a small app from Swift 2.2 to Swift 3. I've gotten rid of the usual errors and bits of mop up required after the auto converter but I've got a run time issue that I can't work out.
I've got a custom class that I am saving to NSUserDefaults with the NSCoding protocol. When I try to decode the encoded object from NSUserDefaults it fails on the guard let duration = decoder.decodeObject(forKey: "duration") as? Int line as duration is printing as nil. Decoding the title string works fine however so at least that line of the encode function is working correctly.
This worked fine in 2.2 and I can't find anything indicating that Swift 3 made changes to the NSCoding. Any help would be much appreciated.
class TimerModel: NSObject, NSCoding, AVAudioPlayerDelegate {
var name: String
var active: Bool
var paused: Bool
var duration: Int
var remainingWhenPaused: Int?
var timerEndTime: Date?
var timerStartTime: Date?
var audioAlert: AlertNoise
var UUID: String
var colorScheme: BaseColor
var alarmRepetitions: Int
var timerRepetitions: Int
var currentTimerRepetition: Int
var audioPlaying: Bool
var player: AVAudioPlayer = AVAudioPlayer()
var countDownTimer: Timer = Timer()
var delegate: timerProtocol? = nil
init(withName name: String, duration: Int, UUID: String, color: BaseColor, alertNoise: AlertNoise, timerRepetitions: Int, alarmRepetitions: Int) {
self.name = name
self.active = false
self.paused = false
self.duration = duration
self.UUID = UUID
self.audioAlert = alertNoise
self.colorScheme = color
self.alarmRepetitions = alarmRepetitions
self.audioPlaying = false
self.timerRepetitions = timerRepetitions
self.currentTimerRepetition = 0
super.init()
}
convenience override init() {
self.init(withName: "Tap Timer 1", duration: 10, UUID: Foundation.UUID().uuidString, color: .Red, alertNoise: .ChurchBell, timerRepetitions: 1, alarmRepetitions: 0)
}
// MARK: NSCoding
required convenience init? (coder decoder: NSCoder) {
print("in init coder:")
print("Name: \(decoder.decodeObject(forKey: "name"))")
print("Duration: \(decoder.decodeObject(forKey: "duration"))")
guard let name = decoder.decodeObject(forKey: "name") as? String
else {
print("init coder name guard failed")
return nil
}
guard let duration = decoder.decodeObject(forKey: "duration") as? Int
else {
print("init coder duration guard failed")
print("duration: \(decoder.decodeObject(forKey: "duration"))")
return nil
}
guard let audioAlertRawValue = decoder.decodeObject(forKey: "audioAlert") as? String
else {
print("init coder audioAlert guard failed")
return nil
}
guard let UUID = decoder.decodeObject(forKey: "UUID") as? String
else {
print("init coder UUID guard failed")
return nil
}
guard let colorSchemeRawValue = decoder.decodeObject(forKey: "colorScheme") as? String
else {
print("init coder colorScheme guard failed")
return nil
}
guard let alarmRepetitions = decoder.decodeObject(forKey: "alarmRepetitions") as? Int
else {
print("init coder alarmRepetitions guard failed")
return nil
}
guard let timerRepetitions = decoder.decodeObject(forKey: "timerRepetitions") as? Int
else {
print("init coder timerRepetitions guard failed")
return nil
}
guard let audioAlert = AlertNoise(rawValue: audioAlertRawValue)
else{
print("No AlertNoise rawValue case found")
return nil
}
guard let colorScheme = BaseColor(rawValue: colorSchemeRawValue)
else{
print("No BaseColor rawValue case found")
return nil
}
print("initCoder guards passed, initing timer")
print("\(name), \(duration), \(UUID), \(colorScheme), \(audioAlert), \(timerRepetitions), \(alarmRepetitions)")
self.init(withName: name, duration: duration, UUID: UUID, color: colorScheme, alertNoise: audioAlert, timerRepetitions: timerRepetitions, alarmRepetitions: alarmRepetitions)
}
func encode(with aCoder: NSCoder) {
aCoder.encode(self.name, forKey: "name")
aCoder.encode(self.duration, forKey: "duration")
aCoder.encode(self.audioAlert.rawValue, forKey: "audioAlert")
aCoder.encode(self.UUID, forKey: "UUID")
aCoder.encode(self.colorScheme.rawValue, forKey: "colorScheme")
aCoder.encode(self.alarmRepetitions, forKey: "alarmRepetitions")
aCoder.encode(self.timerRepetitions, forKey: "timerRepetitions")
}

Answer 1

So it seems the solution is simple if a little unintuitive.
So I encoded the class ivars with the general method encode(self.ivar, forKey: "keyName") however if that ivar is an int it needs to be decoded with decodeInteger(forKey: "keyName") - this entails getting rid of the guard statements as well since this method return an non-optional. Seems odd to have to decode with the integer specific method if it was decoded with the generalist method - this wasn't the case in Swift 2.2.

Answer 2

Excellent answer by SimonBarker and it solved the same issue I had. I eventually applied his solution to my own code and revised it too so that encoding is done with the generalist method. You can "force" encoding with the generalist method by using:
func encode(_ objv: Any?, forKey key: String)
So in your code you could use:
aCoder.encode(self.name as Any?, forKey: "name")
That way self.name is encoded as an object and does not break your existing code, namely: decoder.decodeObject(forKey: "name") as? String
This might not be the most elegant solution, but at least it worked for me without the need to change code that worked beautifully in Swift 2.3, but which was broken in Swift 3...