I have this in Playground using Swift 3, Xcode 8.0:
import Foundation
class Person: NSObject, NSCoding {
var name: String
var age: Int
init(name: String, age: Int) {
self.name = name
self.age = age
}
required convenience init(coder aDecoder: NSCoder) {
let name = aDecoder.decodeObject(forKey: "name") as! String
let age = aDecoder.decodeObject(forKey: "age") as! Int
self.init(
name: name,
age: age
)
}
func encode(with aCoder: NSCoder) {
aCoder.encode(name, forKey: "name")
aCoder.encode(age, forKey: "age")
}
}
create array of Person
let newPerson = Person(name: "Joe", age: 10)
var people = [Person]()
people.append(newPerson)
encode the array
let encodedData = NSKeyedArchiver.archivedData(withRootObject: people)
print("encodedData: \(encodedData))")
save to userDefaults
let userDefaults: UserDefaults = UserDefaults.standard()
userDefaults.set(encodedData, forKey: "people")
userDefaults.synchronize()
check
print("saved object: \(userDefaults.object(forKey: "people"))")
retreive from userDefaults
if let data = userDefaults.object(forKey: "people") {
let myPeopleList = NSKeyedUnarchiver.unarchiveObject(with: data as! Data)
print("myPeopleList: \(myPeopleList)")
}else{
print("There is an issue")
}
just check the archived data
if let myPeopleList = NSKeyedUnarchiver.unarchiveObject(with: encodedData){
print("myPeopleList: \(myPeopleList)")
}else{
print("There is an issue")
}
I'm not able to correctly save the data object to userDefaults, and in addition, the check at the bottom creates the error:
Fatal error: Unexpectedly found nil while unwrapping an Optional value
The "check" line also shows the saved object is nil. Is this an error in my object's NSCoder?
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)
}
}
}