Attempt to set a non-property-list object as an NSUserDefaults

Question

I thought I knew what was causing this error, but I can\'t seem to figure out what I did wrong.

Here is the full error message I am getting:

Attempt to se         


        

Answer 1

Swift with @propertyWrapper

Save Codable object to UserDefault

@propertyWrapper
    struct UserDefault<T: Codable> {
        let key: String
        let defaultValue: T

        init(_ key: String, defaultValue: T) {
            self.key = key
            self.defaultValue = defaultValue
        }

        var wrappedValue: T {
            get {

                if let data = UserDefaults.standard.object(forKey: key) as? Data,
                    let user = try? JSONDecoder().decode(T.self, from: data) {
                    return user

                }

                return  defaultValue
            }
            set {
                if let encoded = try? JSONEncoder().encode(newValue) {
                    UserDefaults.standard.set(encoded, forKey: key)
                }
            }
        }
    }




enum GlobalSettings {

    @UserDefault("user", defaultValue: User(name:"",pass:"")) static var user: User
}

Example User model confirm Codable

struct User:Codable {
    let name:String
    let pass:String
}

How to use it

//Set value 
 GlobalSettings.user = User(name: "Ahmed", pass: "Ahmed")

//GetValue
print(GlobalSettings.user)

Answer 2

It seems rather wasteful to me to run through the array and encode the objects into NSData yourself. Your error BC_Person is a non-property-list object is telling you that the framework doesn't know how to serialize your person object.

So all that is needed is to ensure that your person object conforms to NSCoding then you can simply convert your array of custom objects into NSData and store that to defaults. Heres a playground:

Edit: Writing to NSUserDefaults is broken on Xcode 7 so the playground will archive to data and back and print an output. The UserDefaults step is included in case its fixed at a later point

//: Playground - noun: a place where people can play

import Foundation

class Person: NSObject, NSCoding {
    let surname: String
    let firstname: String

    required init(firstname:String, surname:String) {
        self.firstname = firstname
        self.surname = surname
        super.init()
    }

    //MARK: - NSCoding -
    required init(coder aDecoder: NSCoder) {
        surname = aDecoder.decodeObjectForKey("surname") as! String
        firstname = aDecoder.decodeObjectForKey("firstname") as! String
    }

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

//: ### Now lets define a function to convert our array to NSData

func archivePeople(people:[Person]) -> NSData {
    let archivedObject = NSKeyedArchiver.archivedDataWithRootObject(people as NSArray)
    return archivedObject
}

//: ### Create some people

let people = [Person(firstname: "johnny", surname:"appleseed"),Person(firstname: "peter", surname: "mill")]

//: ### Archive our people to NSData

let peopleData = archivePeople(people)

if let unarchivedPeople = NSKeyedUnarchiver.unarchiveObjectWithData(peopleData) as? [Person] {
    for person in unarchivedPeople {
        print("\(person.firstname), you have been unarchived")
    }
} else {
    print("Failed to unarchive people")
}

//: ### Lets try use NSUserDefaults
let UserDefaultsPeopleKey = "peoplekey"
func savePeople(people:[Person]) {
    let archivedObject = archivePeople(people)
    let defaults = NSUserDefaults.standardUserDefaults()
    defaults.setObject(archivedObject, forKey: UserDefaultsPeopleKey)
    defaults.synchronize()
}

func retrievePeople() -> [Person]? {
    if let unarchivedObject = NSUserDefaults.standardUserDefaults().objectForKey(UserDefaultsPeopleKey) as? NSData {
        return NSKeyedUnarchiver.unarchiveObjectWithData(unarchivedObject) as? [Person]
    }
    return nil
}

if let retrievedPeople = retrievePeople() {
    for person in retrievedPeople {
        print("\(person.firstname), you have been unarchived")
    }
} else {
    print("Writing to UserDefaults is still broken in playgrounds")
}

And Voila, you have stored an array of custom objects into NSUserDefaults

Answer 3

Swift 5 Very Easy way

//MARK:- First you need to encoded your arr or what ever object you want to save in UserDefaults
//in my case i want to save Picture (NMutableArray) in the User Defaults in
//in this array some objects are UIImage & Strings

//first i have to encoded the NMutableArray 
let encodedData = NSKeyedArchiver.archivedData(withRootObject: yourArrayName)
//MARK:- Array save in UserDefaults
defaults.set(encodedData, forKey: "YourKeyName")

//MARK:- When you want to retreive data from UserDefaults
let decoded  = defaults.object(forKey: "YourKeyName") as! Data
yourArrayName = NSKeyedUnarchiver.unarchiveObject(with: decoded) as! NSMutableArray

//MARK: Enjoy this arrry "yourArrayName"

Answer 4

First off, rmaddy's answer (above) is right: implementing NSCoding doesn't help. However, you need to implement NSCoding to use NSKeyedArchiver and all that, so it's just one more step... converting via NSData.

Example methods

- (NSUserDefaults *) defaults {
    return [NSUserDefaults standardUserDefaults];
}

- (void) persistObj:(id)value forKey:(NSString *)key {
    [self.defaults setObject:value  forKey:key];
    [self.defaults synchronize];
}

- (void) persistObjAsData:(id)encodableObject forKey:(NSString *)key {
    NSData *data = [NSKeyedArchiver archivedDataWithRootObject:encodableObject];
    [self persistObj:data forKey:key];
}    

- (id) objectFromDataWithKey:(NSString*)key {
    NSData *data = [self.defaults objectForKey:key];
    return [NSKeyedUnarchiver unarchiveObjectWithData:data];
}

So you can wrap your NSCoding objects in an NSArray or NSDictionary or whatever...

Answer 5

Swift 5: The Codable protocol can be used instead of NSKeyedArchiever.

struct User: Codable {
    let id: String
    let mail: String
    let fullName: String
}

The Pref struct is custom wrapper around the UserDefaults standard object.

struct Pref {
    static let keyUser = "Pref.User"
    static var user: User? {
        get {
            if let data = UserDefaults.standard.object(forKey: keyUser) as? Data {
                do {
                    return try JSONDecoder().decode(User.self, from: data)
                } catch {
                    print("Error while decoding user data")
                }
            }
            return nil
        }
        set {
            if let newValue = newValue {
                do {
                    let data = try JSONEncoder().encode(newValue)
                    UserDefaults.standard.set(data, forKey: keyUser)
                } catch {
                    print("Error while encoding user data")
                }
            } else {
                UserDefaults.standard.removeObject(forKey: keyUser)
            }
        }
    }
}

So you can use it this way:

Pref.user?.name = "John"

if let user = Pref.user {...

Answer 6

To save:

NSUserDefaults *currentDefaults = [NSUserDefaults standardUserDefaults];
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:yourObject];
[currentDefaults setObject:data forKey:@"yourKeyName"];

To Get:

NSData *data = [currentDefaults objectForKey:@"yourKeyName"];
yourObjectType * token = [NSKeyedUnarchiver unarchiveObjectWithData:data];

For Remove

[currentDefaults removeObjectForKey:@"yourKeyName"];