Swift Saving and Retrieving Custom Object from Userdefaults

Swift saving and retrieving custom object from UserDefaults

Swift 4 or later

You can once again save/test your values in a Playground

UserDefaults need to be tested in a real project. Note: No need to force synchronize. If you want to test the coding/decoding in a playground you can save the data to a plist file in the document directory using the keyed archiver. You need also to fix some issues in your class:

class Person: NSObject, NSCoding {
    let name: String
    let age: Int
    init(name: String, age: Int) {
        self.name = name
        self.age = age
    }
    required init(coder decoder: NSCoder) {
        self.name = decoder.decodeObject(forKey: "name") as? String ?? ""
        self.age = decoder.decodeInteger(forKey: "age")
    }
    func encode(with coder: NSCoder) {
        coder.encode(name, forKey: "name")
        coder.encode(age, forKey: "age")
    }
}

Testing:

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()

        do {
            // setting a value for a key
            let newPerson = Person(name: "Joe", age: 10)
            var people = [Person]()
            people.append(newPerson)
            let encodedData = try NSKeyedArchiver.archivedData(withRootObject: people, requiringSecureCoding: false)
            UserDefaults.standard.set(encodedData, forKey: "people")
            // retrieving a value for a key
            if let data = UserDefaults.standard.data(forKey: "people"),
                let myPeopleList = try NSKeyedUnarchiver.unarchiveTopLevelObjectWithData(data) as? [Person] {
                myPeopleList.forEach({print($0.name, $0.age)})  // Joe 10
            }                    
        } catch {
            print(error)
        }
        
    }
}

Storing array of custom objects in UserDefaults

If you really want to persist your data using UserDefaults the easiest way would be to use a class and conform it to NSCoding. Regarding your global var domainSchemas I would recommend using a singleton or extend UserDefaults and create a computed property for it there:

class DomainSchema: NSObject, NSCoding {
    var domain: String
    var schema: String
    init(domain: String, schema: String) {
        self.domain = domain
        self.schema = schema
    }
    required init(coder decoder: NSCoder) {
        self.domain = decoder.decodeObject(forKey: "domain") as? String ?? ""
        self.schema = decoder.decodeObject(forKey: "schema") as? String ?? ""
    }
    func encode(with coder: NSCoder) {
        coder.encode(domain, forKey: "domain")
        coder.encode(schema, forKey: "schema")
    }
}

extension UserDefaults {
    var domainSchemas: [DomainSchema] {
        get {
            guard let data = UserDefaults.standard.data(forKey: "domainSchemas") else { return [] }
            return (try? NSKeyedUnarchiver.unarchiveTopLevelObjectWithData(data)) as? [DomainSchema] ?? []
        }
        set {
            UserDefaults.standard.set(try? NSKeyedArchiver.archivedData(withRootObject: newValue, requiringSecureCoding: false), forKey: "domainSchemas")
        }
    }
}

Usage:

UserDefaults.standard.domainSchemas = [.init(domain: "a", schema: "b"), .init(domain: "c", schema: "d")]

UserDefaults.standard.domainSchemas  // [{NSObject, domain "a", schema "b"}, {NSObject, domain "c", schema "d"}]

If you prefer the Codable approach persisting the Data using UserDefaults as well:

struct DomainSchema: Codable {
    var domain: String
    var schema: String
    init(domain: String, schema: String) {
        self.domain = domain
        self.schema = schema
    }
}

extension UserDefaults {
    var domainSchemas: [DomainSchema] {
        get {
            guard let data = UserDefaults.standard.data(forKey: "domainSchemas") else { return [] }
            return (try? PropertyListDecoder().decode([DomainSchema].self, from: data)) ?? []
        }
        set {
            UserDefaults.standard.set(try? PropertyListEncoder().encode(newValue), forKey: "domainSchemas")
        }
    }
}

Usage:

UserDefaults.standard.domainSchemas = [.init(domain: "a", schema: "b"), .init(domain: "c", schema: "d")]

UserDefaults.standard.domainSchemas  // [{domain "a", schema "b"}, {domain "c", schema "d"}]

I think the best option would be to do not use UserDefaults, create a singleton "shared instance", declare a domainSchemas property there and save your json Data inside a subdirectory of you application support directory:

extension URL {
    static var domainSchemas: URL {
        let applicationSupport = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask).first!
        let bundleID = Bundle.main.bundleIdentifier ?? "company name"
        let subDirectory = applicationSupport.appendingPathComponent(bundleID, isDirectory: true)
        try? FileManager.default.createDirectory(at: subDirectory, withIntermediateDirectories: true, attributes: nil)
        return subDirectory.appendingPathComponent("domainSchemas.json")
    }
}

class Shared {
    static let instance = Shared()
    private init() { }
    var domainSchemas: [DomainSchema] {
        get {
            guard let data = try? Data(contentsOf: .domainSchemas) else { return [] }
            return (try? JSONDecoder().decode([DomainSchema].self, from: data)) ?? []
        }
        set {
            try? JSONEncoder().encode(newValue).write(to: .domainSchemas)
        }
    }
}

Usage:

Shared.instance.domainSchemas = [.init(domain: "a", schema: "b"), .init(domain: "c", schema: "d")]

Shared.instance.domainSchemas  // [{domain "a", schema "b"}, {domain "c", schema "d"}]

Retrieving custom Object from NSUserDefaults

Step 1.

Make your struct Codable. The compiler will write all of the functions for you if all of the members of your struct are Codable and fortunately String is Codable so its just:

struct Object: Codable {
  var heading : String!
  var imageName: String!
}

Step 2.

The problem with Codable is that it converts to and from Data, but you want to convert to and from a Dictionary. Fortunately JSONSerialization converts from Data to Dictionary so make a new protocol and give it a default implementation with a protocol extension:

protocol JSONRepresentable {
  init?(json: [String: Any])
  func json() -> [String: Any]
}
extension JSONRepresentable where Self: Codable {
  init?(json: [String:Any]) {
    guard let value = (try? JSONSerialization.data(withJSONObject: json, options: []))
      .flatMap ({ try? JSONDecoder().decode(Self.self, from: $0) }) else {
        return nil
    }
    self = value
  }
  func json() -> [String:Any] {
    return (try? JSONEncoder().encode(self))
      .flatMap { try? JSONSerialization.jsonObject(with: $0, options: []) } as? [String: Any] ?? [:]
  }
}

Step 3.

Conform your struct to JSONRepresentable

struct Object: Codable, JSONRepresentable {
  var heading : String!
  var imageName: String!
}

Step 4.

Place your object into Userdefaults and get it out again:

let o = Object.init(heading: "s", imageName: "a").json()
UserDefaults.standard.set(o, forKey: "test")
print(Object.init(json: UserDefaults.standard.dictionary(forKey: "test") ?? [:]))

Here is the whole playground if you want to try:

import UIKit

struct Object: Codable, JSONRepresentable {
  var heading : String!
  var imageName: String!
}

protocol JSONRepresentable {
  init?(json: [String: Any])
  func json() -> [String: Any]
}
extension JSONRepresentable where Self: Codable {
  init?(json: [String:Any]) {
    guard let value = (try? JSONSerialization.data(withJSONObject: json, options: []))
      .flatMap ({ try? JSONDecoder().decode(Self.self, from: $0) }) else {
        return nil
    }
    self = value
  }
  func json() -> [String:Any] {
    return (try? JSONEncoder().encode(self))
      .flatMap { try? JSONSerialization.jsonObject(with: $0, options: []) } as? [String: Any] ?? [:]
  }
}

let o = Object.init(heading: "s", imageName: "a").json()
UserDefaults.standard.set(o, forKey: "test")
print(Object.init(json: UserDefaults.standard.dictionary(forKey: "test") ?? [:]))

Swift 4: Save and retrieve an array of custom objects (with nested custom objects) to UserDefaults

Go ahead and implement NSCoding for the other two custom objects. Also, change your decodeObject to decodeInteger on all Integers of your custom objects, and remove the "as! Int" from them. Then, do this:

let userDefaults = UserDefaults.standard
let encodedData = NSKeyedArchiver.archivedData(withRootObject: self.saleArray)
userDefaults.set(encodedData, forKey: "sales")

To retrieve the data, do this:

let newArray = NSKeyedUnarchiver.unarchiveObject(with: data as! Data) as! [SaleObject]

After you have it working, go back and research Codable. Enjoy!

How can I save an object of a custom class in Userdefaults in swift 5/ Xcode 10.2

Vadian's answer is correct, you cannot use NSKeyedArchiver with structs. Having all your objects conform to Codable is the best way to reproduce the behavior you are looking for. I do what Vadian does, but I you can also use protocol extensions to make this safer.

import UIKit

struct Patient: Codable {
    var name: String
    var number: String
    var resultArray: [Diagnose]
    var diagnoseArray: [Diagnose]
}

struct Diagnose: Codable {
    var name: String
    var treatments: [Treatment]
    var isPositiv : Bool
    var isExtended : Bool
}

struct Treatment: Codable {
    var name: String
    var wasMade : Bool
}

let newPatient = Patient(name: "John Doe",
                         number: "123",
                         resultArray: [Diagnose(name: "Result", treatments: [Treatment(name: "Treat1", wasMade: false)], isPositiv: false, isExtended: false)],
                         diagnoseArray: [Diagnose(name: "Diagnose", treatments: [Treatment(name: "Treat2", wasMade: false)], isPositiv: false, isExtended: false)])
let patientList: [Patient] = [newPatient]

Introduce a protocol to manage the encoding and saving of objects.

This does not have to inherit from Codable but it does for this example for simplicity.

/// Objects conforming to `CanSaveToDisk` have a save method and provide keys for saving individual objects or a list of objects.
protocol CanSaveToDisk: Codable {

    /// Provide default logic for encoding this value.
    static var defaultEncoder: JSONEncoder { get }

    /// This key is used to save the individual object to disk. This works best by using a unique identifier.
    var storageKeyForObject: String { get }

    /// This key is used to save a list of these objects to disk. Any array of items conforming to `CanSaveToDisk` has the option to save as well.
    static var storageKeyForListofObjects: String { get }

    /// Persists the object to disk.
    ///
    /// - Throws: useful to throw an error from an encoder or a custom error if you use stage different from user defaults like the keychain
    func save() throws

}

Using protocol extensions we add an option to save an array of these objects.

extension Array where Element: CanSaveToDisk {

    func dataValue() throws -> Data {
        return try Element.defaultEncoder.encode(self)
    }

    func save() throws {
        let storage = UserDefaults.standard
        storage.set(try dataValue(), forKey: Element.storageKeyForListofObjects)
    }

}

We extend our patient object so it can know what to do when saving.

I use "storage" so that this could be swapped with NSKeychain. If you are saving sensitive data (like patient information) you should be using the keychain instead of UserDefaults. Also, make sure you comply with security and privacy best practices for health data in whatever market you're offering your app. Laws can be a very different experience between countries. UserDefaults might not be safe enough storage.

There are lots of great keychain wrappers to make things easier. UserDefaults simply sets data using a key. The Keychain does the same. A wrapper like https://github.com/evgenyneu/keychain-swift will behave similar to how I use UserDefaults below. I have commented out what the equivalent use would look like for completeness.

extension Patient: CanSaveToDisk {

    static var defaultEncoder: JSONEncoder {
        let encoder = JSONEncoder()
        // add additional customization here
        // like dates or data handling
        return encoder
    }

    var storageKeyForObject: String {
        // "com.myapp.patient.123"
        return "com.myapp.patient.\(number)"
    }

    static var storageKeyForListofObjects: String {
        return "com.myapp.patientList"
    }

    func save() throws {

        // you could also save to the keychain easily
        //let keychain = KeychainSwift()
        //keychain.set(dataObject, forKey: storageKeyForObject)

        let data = try Patient.defaultEncoder.encode(self)
        let storage = UserDefaults.standard
        storage.setValue(data, forKey: storageKeyForObject)
    }
}

Saving is simplified, check out the 2 examples below!

do {

    // saving just one patient record
    // this saves this patient to the storageKeyForObject
    try patientList.first?.save()

    // saving the entire list
    try patientList.save()


} catch { print(error) }

Save Dictionary of custom objects in Swift using UserDefaults

You need to make your class NSCoding compliant and inherit from NSObject. Change your Contact declaration to class Contact: NSObject, NSCoding {. And Btw conditionally cast to force unwrap it later is pointless. decoder.decodeObject(forKey: "name") as! String

class Contact: NSObject, NSCoding {
    var name = String()
    var phone = String()
    init(name: String, phone: String){
        self.name=name
        self.phone=phone
    }
    required init(coder decoder: NSCoder){
        self.name = decoder.decodeObject(forKey: "name") as! String
        self.phone = decoder.decodeObject(forKey: "phone") as! String
    }
    func encode(with coder: NSCoder){
        coder.encode(name, forKey: "name")
        coder.encode(phone, forKey: "phone")
    }
}

Testing:

let contactDictionary = ["A":[Contact(name: "Annabel",phone: "000")]]

let encodedData = NSKeyedArchiver.archivedData(withRootObject: contactDictionary)
UserDefaults.standard.set(encodedData, forKey: "contactDictionary")

if let data = UserDefaults.standard.data(forKey: "contactDictionary") {
    print("yep")
    let contactDictionary2 = NSKeyedUnarchiver.unarchiveObject(with: data) as! [String : [Contact]]
}
else{
    print("nope")
}

Saving Array of Custom Object

You are trying to save an array of custom objects to UserDefaults. Your custom object isn't a property list object You should use Codable to save non-property list object in UserDefaults like this.

Swift 4

Custom Class

class Sheet: Codable {
  var title = ""
  var content = ""
}

ViewController.swift

class ViewController: UIViewController {

    var notes = [Sheet]()

    override func viewDidLoad() {
        super.viewDidLoad()

        getSheets()
        addSheets()
        getSheets()
    }
    func getSheets()
    {
        if let storedObject: Data = UserDefaults.standard.data(forKey: "notes")
        {
            do
            {
                notes = try PropertyListDecoder().decode([Sheet].self, from: storedObject)
                for note in notes
                {
                    print(note.title)
                    print(note.content)
                }
            }
            catch
            {
                print(error.localizedDescription)
            }
        }
    }
    func addSheets()
    {
        let sheet1 = Sheet()
        sheet1.title = "title1"
        sheet1.content = "content1"

        let sheet2 = Sheet()
        sheet2.title = "title1"
        sheet2.content = "content1"

        notes = [sheet1,sheet2]
        do
        {
            UserDefaults.standard.set(try PropertyListEncoder().encode(notes), forKey: "notes")
            UserDefaults.standard.synchronize()
        }
        catch
        {
            print(error.localizedDescription)
        }
    }
}

How to use NSUserDefaults to store an array of custom classes in Swift?

Your Person class should look like this:

Swift 3:

class Person : NSObject, NSCoding{

    // Person dictionary variable
    var name: String?
    var age: String?
    var html_url: String?

    init(json: NSDictionary) { // Dictionary object
        self.name = json["name"] as? String
        self.age = json["age"] as? String
        self.html_url = json["html_url"] as? String // Location of the JSON file
    }

    required init?(coder aDecoder: NSCoder) {

        self.name = aDecoder.decodeObjectForKey("name") as? String;
        self.age = aDecoder.decodeObjectForKey("age") as? String;
        self.html_url = aDecoder.decodeObjectForKey("html") as? String;
    }

    func encodeWithCoder(aCoder: NSCoder) {
        aCoder.encodeObject(self.name, forKey: "name");
        aCoder.encodeObject(self.age, forKey: "age");
        aCoder.encodeObject(self.html_url, forKey: "html");
    }
}

And here you have an example of saving and retrieving the array from NSUserDefaults:

let p = Person()
p.name = "person1"
p.age = "12"
p.html_url = "www.google.ro"

let p2 = Person()
p2.name = "person2"
p2.age = "11"
p2.html_url = "www.google.ro"

let array = [p, p2]

let userDefaults = NSUserDefaults.standardUserDefaults()
userDefaults.setValue(NSKeyedArchiver.archivedDataWithRootObject(array), forKey: "persons")
userDefaults.synchronize()

let array : [Person]
array = NSKeyedUnarchiver.unarchiveObjectWithData(userDefaults.objectForKey("persons") as! NSData) as! [Person]
print("\(array[0].name)\(array[1].name)")

Swift 4:

class Person : NSObject, NSCoding{

    // Person dictionary variable
    var name: String?
    var age: String?
    var html_url: String?

    init(json: NSDictionary) { // Dictionary object
        self.name = json["name"] as? String
        self.age = json["age"] as? String
        self.html_url = json["html_url"] as? String // Location of the JSON file
    }

    required init?(coder aDecoder: NSCoder) {
        self.name = aDecoder.decodeObject(forKey: "name") as? String;
        self.age = aDecoder.decodeObject(forKey: "age") as? String;
        self.html_url = aDecoder.decodeObject(forKey: "html") as? String;
    }

    func encode(with aCoder: NSCoder) {
        aCoder.encode(self.name, forKey: "name");
        aCoder.encode(self.age, forKey: "age");
        aCoder.encode(self.html_url, forKey: "html");
    }
}

Save custom objects into NSUserDefaults

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")
    }
}

Swift Saving and Retrieving Custom Object from Userdefaults