Save custom objects into NSUserDefaults

Question

I'm having a news ViewController and a TeamViewController. The TeamViewController contain a tableView of teamObjects which when selected is added into array. I want to add this array into NSUserDefaults so i can access them from the NewsController which contain a url request where the teamObjects is needed. However i keep getting:

'Attempt to insert non-property list object ( "" ) for key teams'

I'm open for other suggestions if there is better ways than storing it in NSUserDefaults

didSelectRowAtIndexPath method

override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
    tableView.deselectRowAtIndexPath(indexPath, animated: true)


    let team = self.teamArray[indexPath.row] as Team
    var removed = false

    for (index, value) in enumerate(self.teamSelected) {
        if (value == team) {
            self.teamSelected.removeAtIndex(index)
            removed = true
        }
    }

    if (!removed) {
        self.teamSelected.append(team)
    }

    var userDefaults = NSUserDefaults.standardUserDefaults()
    userDefaults.setValue(self.teamSelected, forKey: "teams")
    userDefaults.synchronize()

    tableView.reloadData()
}

My object

class Team: NSObject{
    var id: Int!
    var name: NSString!
    var shortname: NSString!


    init(id: Int, name:NSString, shortname: NSString) {
        self.id = id
        self.name = name
        self.shortname = shortname

    }

}

score 246 · Accepted Answer · edited Jul 01 '22 at 15:03

246

Actually, you will need to archive the custom object into NSData then save it to user defaults and retrieve it from user defaults and unarchive it again. You can archive it like this

let teams = [Team(id: 1, name: "team1", shortname: "t1"), Team(id: 2, name: "team2", shortname: "t2")]

var userDefaults = UserDefaults.standard
let encodedData: Data = NSKeyedArchiver.archivedData(withRootObject: teams)
userDefaults.set(encodedData, forKey: "teams")

and unarchive it like this

let decoded  = userDefaults.data(forKey: "teams")
let decodedTeams = NSKeyedUnarchiver.unarchiveObject(with: decoded) as! [Team]

But if you just did that you will get

.Team encodeWithCoder:]: unrecognized selector sent to instance

You will have to make Team conform to NSCoding just like this

class Team: NSObject, NSCoding {
    var id: Int
    var name: String
    var shortname: String


    init(id: Int, name: String, shortname: String) {
        self.id = id
        self.name = name
        self.shortname = shortname

    }

    required convenience init(coder aDecoder: NSCoder) {
        let id = aDecoder.decodeInteger(forKey: "id")
        let name = aDecoder.decodeObject(forKey: "name") as! String
        let shortname = aDecoder.decodeObject(forKey: "shortname") as! String
        self.init(id: id, name: name, shortname: shortname)
    }

    func encode(with aCoder: NSCoder) {
        aCoder.encode(id, forKey: "id")
        aCoder.encode(name, forKey: "name")
        aCoder.encode(shortname, forKey: "shortname")
    }
}

edited Jul 01 '22 at 15:03

Jake Chasan

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answered May 01 '15 at 13:00

mohamede1945

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How do you deal with the error caused by this line `let decodedTeams = NSKeyedUnarchiver.unarchiveObjectWithData(decoded) as! [Team]` (the error being `Can throw but the error is not handled`)? – afkatja Nov 09 '16 at 16:09
@afkatja Check the updated code-- it should work now :) – Fluidity Nov 15 '16 at 17:56
1

Thank you in particular for including decodeInteger in this example, that had me noticed that type casting really counts in this function. – Tamás Sengel Jun 19 '17 at 15:23
can we save UIImage with this method? – Talha Ahmad Khan Dec 03 '17 at 06:24
You have to convert it to NSData. You can't save UIImage directly. – mohamede1945 Dec 03 '17 at 18:19
1

"required convenience init(coder aDecoder: NSCoder)" this method is not getting called for me, any help appreciated – kalpa Mar 16 '18 at 09:52
I wonder if this can be done with struct? – Sentry.co Sep 19 '18 at 14:14
what if team had a custom object inside it , do we need to add NSCoding to that custom object's class also?? – Ankit Kumar Gupta Mar 14 '19 at 07:03

Malav Soni · Answer 2 · 2020-01-28T07:37:57.407

You can try NSKeyedUnarchiver, like below

Here i stored UIColor Object in UserDefault You can change it with your object

 NSData *colorData = [NSKeyedArchiver archivedDataWithRootObject:color];
[[NSUserDefaults standardUserDefaults] setObject:colorData forKey:@"myColor"];

and to retrive that

NSData *colorData = [[NSUserDefaults standardUserDefaults] objectForKey:@"myColor"];
UIColor *color = [NSKeyedUnarchiver unarchiveObjectWithData:colorData];

Note : This is Objective C but I hope you can covert this in Swift

Hope this solve your problem

Update : Swift 5

Archive in Swift

do{
    let colorAsData = try NSKeyedArchiver.archivedData(withRootObject: UIColor.red, requiringSecureCoding: true)
    UserDefaults.standard.set(colorAsData, forKey: "myColor")
    UserDefaults.standard.synchronize()
}catch (let error){ 
    #if DEBUG
        print("Failed to convert UIColor to Data : \(error.localizedDescription)")
    #endif
}

Unarchive in Swift

do{
    if let colorAsData = UserDefaults.standard.object(forKey: "myColor") as? Data{
        if let color = try NSKeyedUnarchiver.unarchivedObject(ofClasses: [UIColor.self], from: colorAsData){
            // Use Color
        }
    }
}catch (let error){
    #if DEBUG
        print("Failed to convert UIColor to Data : \(error.localizedDescription)")
    #endif
}

due to uncaught exception 'NSInvalidArgumentException', reason: '-[Striky.Team encodeWithCoder:]: unrecognized selector — Peter Pik, May 01 '15 at 12:51

Save custom objects into NSUserDefaults

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