Converting Swift Array to NSData causes an error

Question

I have two arrays

var questions: [Question]!
var types: [[Type]]!

I am trying to convert those two arrays to NSData. I do like below

let typesData = NSKeyedArchiver.archivedDataWithRootObject(types)
let questionsData = NSKeyedArchiver.archivedDataWithRootObject(questions)

As soon as it hits typesData, the app crashes and throws an error like following:

*** NSForwarding: warning: object 0x15e5a4100 of class '(app Name).Type' does not implement methodSignatureForSelector: -- trouble ahead Unrecognized selector -[(app Name).Type replacementObjectForKeyedArchiver:]

I am assuming it's causing an error since those arrays has custom types. Is there any way I can convert those arrays to NSData? Any solutions for solving this problem will be appreciated.

seems like u need to implements NSCoding for them then only u can save it as NSData — Tj3n
– Tj3n, Commented Jan 26, 2016 at 7:55
@Larme, they do not have initWithCoder function. Do I need to implement it? — Kahsn
– Kahsn, Commented Jan 26, 2016 at 7:57
developer.apple.com/library/ios/documentation/Cocoa/Conceptual/… — Larme
– Larme, Commented Jan 26, 2016 at 7:58

Tj3n · Accepted Answer · 2016-01-26 08:02:23Z

1

For swift, you need to implement this in your Object (Question, Type) class like so:

class ItemObject:NSObject, NSCoding {
    var itemName = ""
    var itemCheck = false

    func encodeWithCoder(aCoder: NSCoder) {
        aCoder.encodeObject(itemName, forKey:"itemName")
        aCoder.encodeBool(itemCheck, forKey:"itemCheck")
    }


    required init (coder aDecoder: NSCoder) {
        self.itemName = aDecoder.decodeObjectForKey("itemName") as! String
        self.itemCheck = aDecoder.decodeBoolForKey("itemCheck")
    }

    override init() {
        super.init()
    }
}

This is also required for store custom object to NSUserDefaults and CoreData

answered Jan 26, 2016 at 8:02

Tj3n

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