The NSUserDefaults class provides a programmatic interface for interacting with the defaults system. The defaults system allows an app to customize its behavior to match a user's preferences. For example, you can allow users to specify their preferred units of measurement or media playback speed.
We access the shared defaults object through the standard class property of the UserDefaults class. We then create a dictionary of type [String:String] and store the dictionary in the user's defaults database by invoking the set(_:forKey:) method of the UserDefaults database.
The code you posted tries to save an array of custom objects to NSUserDefaults
. You can't do that. Implementing the NSCoding
methods doesn't help. You can only store things like NSArray
, NSDictionary
, NSString
, NSData
, NSNumber
, and NSDate
in NSUserDefaults
.
You need to convert the object to NSData
(like you have in some of the code) and store that NSData
in NSUserDefaults
. You can even store an NSArray
of NSData
if you need to.
When you read back the array you need to unarchive the NSData
to get back your BC_Person
objects.
Perhaps you want this:
- (void)savePersonArrayData:(BC_Person *)personObject {
[mutableDataArray addObject:personObject];
NSMutableArray *archiveArray = [NSMutableArray arrayWithCapacity:mutableDataArray.count];
for (BC_Person *personObject in mutableDataArray) {
NSData *personEncodedObject = [NSKeyedArchiver archivedDataWithRootObject:personObject];
[archiveArray addObject:personEncodedObject];
}
NSUserDefaults *userData = [NSUserDefaults standardUserDefaults];
[userData setObject:archiveArray forKey:@"personDataArray"];
}
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
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"];
class ArchiveUtil {
private static let PeopleKey = "PeopleKey"
private static func archivePeople(people : [Human]) -> NSData {
return NSKeyedArchiver.archivedData(withRootObject: people as NSArray) as NSData
}
static func loadPeople() -> [Human]? {
if let unarchivedObject = UserDefaults.standard.object(forKey: PeopleKey) as? Data {
return NSKeyedUnarchiver.unarchiveObject(with: unarchivedObject as Data) as? [Human]
}
return nil
}
static func savePeople(people : [Human]?) {
let archivedObject = archivePeople(people: people!)
UserDefaults.standard.set(archivedObject, forKey: PeopleKey)
UserDefaults.standard.synchronize()
}
}
class Human: NSObject, NSCoding {
var name:String?
var age:Int?
required init(n:String, a:Int) {
name = n
age = a
}
required init(coder aDecoder: NSCoder) {
name = aDecoder.decodeObject(forKey: "name") as? String
age = aDecoder.decodeInteger(forKey: "age")
}
public func encode(with aCoder: NSCoder) {
aCoder.encode(name, forKey: "name")
aCoder.encode(age, forKey: "age")
}
}
var people = [Human]()
people.append(Human(n: "Sazzad", a: 21))
people.append(Human(n: "Hissain", a: 22))
people.append(Human(n: "Khan", a: 23))
ArchiveUtil.savePeople(people: people)
let others = ArchiveUtil.loadPeople()
for human in others! {
print("name = \(human.name!), age = \(human.age!)")
}
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