Unable to decode a NSObject in Swift

Question

I am having a problem decoding an object after I encode it in Swift.

Here is my class:

class Player: NSObject, NSCoding {

    var score:Int = 0

init(difficulty: Int!) {
    super.init()

}


required init(coder aDecoder: NSCoder) {
    score = aDecoder.decodeObjectForKey("score") as Int
}

func encodeWithCoder(aCoder: NSCoder) {
    aCoder.encodeObject(score, forKey: "score")
}

Here is when I am encoding and decoding:

let data = NSKeyedArchiver.archivedDataWithRootObject(player)
let newPlayer = NSKeyedUnarchiver.unarchiveObjectWithData(data) as Player

It crashes everytime when I try to unarchive it. Anybody have any reasons why?

P.S. I have no idea why my code isn't formatted. I have it indented 4 spaces over! Sorry about that!

score 1 · Accepted Answer · answered Sep 25 '14 at 21:08

1

Here is what I did to get it working:

Created an instance of player in my App Delegate
You can call this anywhere if your application UIApplication.sharedApplication().player

answered Sep 25 '14 at 21:08

dhint4

1,132
2
11
25

Steve Rosenberg · Answer 2 · 2014-09-21T02:17:48.360

This should work. I will post a separate answer if you wish to save an array of Player objects.

Two NSObject classes:

import Foundation

class Player: NSObject {

    var score:Int = 0

    func encodeWithCoder(aCoder: NSCoder!) {
        aCoder.encodeInteger(score, forKey: "score")
    }

    init(coder aDecoder: NSCoder!) {
        score = aDecoder.decodeIntegerForKey("score")
    }

    override init() {
    }
}

class ArchivePlayer:NSObject {

    var documentDirectories:NSArray = []
    var documentDirectory:String = ""
    var path:String = ""

    func savePlayer(#player: Player) {
        documentDirectories = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
        documentDirectory = documentDirectories.objectAtIndex(0) as String
        path = documentDirectory.stringByAppendingPathComponent("players.archive")

        if NSKeyedArchiver.archiveRootObject(player, toFile: path) {
            println("Success writing to file!")
        } else {
            println("Unable to write to file!")
        }
    }

    func retrievePlayer() -> NSObject {
        var dataToRetrieve = Player()
        documentDirectories = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
        documentDirectory = documentDirectories.objectAtIndex(0) as String
        path = documentDirectory.stringByAppendingPathComponent("players.archive")
        if let dataToRetrieve2 = NSKeyedUnarchiver.unarchiveObjectWithFile(path) as? Player {
            dataToRetrieve = dataToRetrieve2 as Player
        }
        return(dataToRetrieve)
    }
}

And then in the ViewController:

import UIKit

class ViewController: UIViewController {

    var player = Player()

    override func viewDidLoad() {
        super.viewDidLoad()

        player.score = 22
        ArchivePlayer().savePlayer(player: player)
        let playerToRetrieve = ArchivePlayer().retrievePlayer() as Player
        println(playerToRetrieve.score)
    }
}

This demonstrates archiving and unarchiving to file. Printing "Success writing to file!" to demonstrate the archiving. Printing the stored object player.score to demonstrate unarchiving.

Thank you for both of your answers. I instead created an instance of player in my App Delegate and called used using UIApplication.sharedApplication().player — dhint4, Sep 25 '14 at 21:07

score 0 · Answer 3 · answered Sep 21 '14 at 02:17

For storing arrays of Player objects here are the NSObject classes:

import Foundation

class Player: NSObject {

    var score:Int = 0

    func encodeWithCoder(aCoder: NSCoder!) {
        aCoder.encodeInteger(score, forKey: "score")
    }

    init(coder aDecoder: NSCoder!) {
        score = aDecoder.decodeIntegerForKey("score")
    }

    override init() {
    }
}

class ArchivePlayer:NSObject {

    var documentDirectories:NSArray = []
    var documentDirectory:String = ""
    var path:String = ""

    func savePlayerArray(#playerArray: [Player]) {
        documentDirectories = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
        documentDirectory = documentDirectories.objectAtIndex(0) as String
        path = documentDirectory.stringByAppendingPathComponent("playersArray.archive")

        if NSKeyedArchiver.archiveRootObject(playerArray, toFile: path) {
            println("Success writing to file!")
        } else {
            println("Unable to write to file!")
        }
    }

    func retrievePlayerArray() -> NSObject {
        var dataToRetrieve = [Player]()
        documentDirectories = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
        documentDirectory = documentDirectories.objectAtIndex(0) as String
        path = documentDirectory.stringByAppendingPathComponent("playersArray.archive")
        if let dataToRetrieve2 = NSKeyedUnarchiver.unarchiveObjectWithFile(path) as? [Player] {
            dataToRetrieve = dataToRetrieve2
        }
        return(dataToRetrieve)
    }
}

Here is the ViewController:

import UIKit

class ViewController: UIViewController {

    var player1 = Player()
    var player2 = Player()
    var player3 = Player()
    var playerArchiveArray = [Player]()

    override func viewDidLoad() {
        super.viewDidLoad()


        player1.score = 12
        player2.score = 22
        player3.score = 32
        playerArchiveArray = [player1, player2, player3]
        ArchivePlayer().savePlayerArray(playerArray: playerArchiveArray)
        var playerRetrieveArray = ArchivePlayer().retrievePlayerArray() as [Player]

        for player in playerRetrieveArray {
            println(player.score)
        }
    }
}

Unable to decode a NSObject in Swift

3 Answers3