How to save an array of custom structs to plist swift

I’m trying to save alert data to a plist, it is in the form of an array of the class alertData, all the info i can find points to encoding it, and then putting it in the array, but i’m confused as to what this does? And i also can’t figure out how to do it, here’s my playground: Any help would be great

The class (i’m trying to save an array of these)

public class alertData: NSObject, NSCoding {
//Properties of the timer data - make optionals optional i.e. alert count etc.

var alertCounter: NSTimeInterval?
var alertText: String?
var alertColor: UIColor?
var alertColorIndex: Int?


//initialisation
init(alertCounter: Double, alertText: String, alertColor: UIColor, alertColourIndex: Int) {

    self.alertCounter = alertCounter
    self.alertText = alertText
    self.alertColor = alertColor
    self.alertColorIndex = alertColourIndex
}

public required init(coder aDecoder: NSCoder) {
    alertCounter = aDecoder.decodeDoubleForKey("Item1")
    alertText = aDecoder.decodeObjectForKey("Item2") as? String
    alertColor = aDecoder.decodeObjectForKey("Item3") as? UIColor
    alertColorIndex = aDecoder.decodeIntegerForKey("Item4")
}

public func encodeWithCoder(aCoder: NSCoder) {
    alertCounter = aCoder.decodeDoubleForKey("Item1")
    alertText = aCoder.decodeObjectForKey("Item2") as? String
    alertColor = aCoder.decodeObjectForKey("Item3") as? UIColor
    alertColorIndex = aCoder.decodeIntegerForKey("Item4")
}
}

The array (becomes populated when i add alert data in the app):

var alertDataSource: [alertData] = []

And to encode it:

let archive = NSKeyedArchiver.archivedDataWithRootObject(self.alertDataSource)
            print(archive)

And to extract it:

let result = NSKeyedUnarchiver.unarchiveObjectWithData(archive)
            print(result)

Thanks in advance for any tips / advice

You’re not meant to call encodeWithCoder() yourself. Use NSKeyedArchiver and NSKeyedUnarchiver. The init(coder:) and encodeWithCoder() will be called as needed by the archiver / unarchiver.

Place your NSCoding-compliant alertData instances (this should really be AlertData since class names should be proper case) into an array (or dictionary if you please) and do this:

let archive = NSKeyedArchiver.archivedDataWithRootObject(yourArrayOfAlertData)

In this case, archive will be an NSData instance.

Update

Actually, I guess I missed it the first time, but your encode...() method isn’t right. At all. Consider the difference with:

public func encodeWithCoder(aCoder: NSCoder) {
    aCoder.encodeDouble(alertCounter, forKey:"Item1")
    aCoder.encodeObject(alertText, forKey:"Item2")
    aCoder.encodeObject(alertColor , forKey:"Item3")
    aCoder.encodeInteger(alertColorIndex, forKey:"Item4")
}

(Also consider naming your keys the same as their properties, like "alertCounter" for alertCounter.)