Swift 4

We need to serialize our swift object to save it into userDefaults.

In swift 4 we can use Codable protocol, which makes our life easy on serialization and JSON parsing

Workflow(Save swift object in UserDefaults):

1. Confirm Codable protocol to model class(class Place : Codable).
2. Create object of class.
3. Serialize that class using JsonEncoder class.
4. Save serialized(Data) object to UserDefaults.

Workflow(Get swift object from UserDefaults):

1. Get data from UserDefaults(Which will return Serialized(Data) object)
2. Decode Data using JsonDecoder class

Swift 4 Code:

class Place: Codable {    var latitude: Double    var longitude: Double    init(lat : Double, long: Double) {        self.latitude = lat        self.longitude = long    }    public static func savePlaces(){        var placeArray = [Place]()        let place1 = Place(lat: 10.0, long: 12.0)        let place2 = Place(lat: 5.0, long: 6.7)        let place3 = Place(lat: 4.3, long: 6.7)        placeArray.append(place1)        placeArray.append(place2)        placeArray.append(place3)        let placesData = try! JSONEncoder().encode(placeArray)        UserDefaults.standard.set(placesData, forKey: "places")    }    public static func getPlaces() -> [Place]?{        let placeData = UserDefaults.standard.data(forKey: "places")        let placeArray = try! JSONDecoder().decode([Place].self, from: placeData!)        return placeArray    }}

From the Property List Programming Guide:

If a property-list object is a container (that is, an array or dictionary), all objects contained within it must also be property-list objects. If an array or dictionary contains objects that are not property-list objects, then you cannot save and restore the hierarchy of data using the various property-list methods and functions.

You'll need to convert the object to and from an NSData instance using NSKeyedArchiver and NSKeyedUnarchiver.

For example:

func savePlaces(){    let placesArray = [Place(lat: 123, lng: 123, name: "hi")]    let placesData = NSKeyedArchiver.archivedDataWithRootObject(placesArray)    NSUserDefaults.standardUserDefaults().setObject(placesData, forKey: "places")}func loadPlaces(){    let placesData = NSUserDefaults.standardUserDefaults().objectForKey("places") as? NSData    if let placesData = placesData {        let placesArray = NSKeyedUnarchiver.unarchiveObjectWithData(placesData) as? [Place]        if let placesArray = placesArray {            // do something…        }    }}

Swift 3 & 4

The following is the complete example code in Swift 3 & 4.

import Foundationclass Place: NSObject, NSCoding {    var latitude: Double    var longitude: Double    var name: String    init(latitude: Double, longitude: Double, name: String) {        self.latitude = latitude        self.longitude = longitude        self.name = name    }    required init?(coder aDecoder: NSCoder) {        self.latitude = aDecoder.decodeDouble(forKey: "latitude")        self.longitude = aDecoder.decodeDouble(forKey: "longitude")        self.name = aDecoder.decodeObject(forKey: "name") as? String ?? ""    }    func encode(with aCoder: NSCoder) {        aCoder.encode(latitude, forKey: "latitude")        aCoder.encode(longitude, forKey: "longitude")        aCoder.encode(name, forKey: "name")    }}func savePlaces() {    var placesArray: [Place] = []    placesArray.append(Place(latitude: 12, longitude: 21, name: "place 1"))    placesArray.append(Place(latitude: 23, longitude: 32, name: "place 2"))    placesArray.append(Place(latitude: 34, longitude: 43, name: "place 3"))    let placesData = NSKeyedArchiver.archivedData(withRootObject: placesArray)    UserDefaults.standard.set(placesData, forKey: "places")}func loadPlaces() {    guard let placesData = UserDefaults.standard.object(forKey: "places") as? NSData else {        print("'places' not found in UserDefaults")        return    }    guard let placesArray = NSKeyedUnarchiver.unarchiveObject(with: placesData as Data) as? [Place] else {        print("Could not unarchive from placesData")        return    }    for place in placesArray {        print("")        print("place.latitude: \(place.latitude)")        print("place.longitude: \(place.longitude)")        print("place.name: \(place.name)")    }}

Example Use:

savePlaces()loadPlaces()

Console Output:

place.latitude: 12.0place.longitude: 21.0place.name: 'place 1'place.latitude: 23.0place.longitude: 32.0place.name: 'place 2'place.latitude: 34.0place.longitude: 43.0place.name: 'place 3'