How to set a class instance to userdefaults in swift? - iphone

Question

I researched it, but I couldnt find the right solution. I want to set a class instance to userDefaults. Assume that I have a class like this:
class Person {
var id: Int
var name: String
var email: String
init() {
self.id = 0
self.name = ""
self.email = ""
}
}
I created an instance from person class, after WebService call finished and I did:
var person: Person = Person()
person.id = personJSON.valueForKey(WSConstants.USER_ID) as Int
person.name = personJSON.valueForKey(WSConstants.USER_NAME) as String
person.email = personJSON.valueForKey(WSConstants.USER_EMAIL) as String
and then, I actually want to do this:
var userDefaults = NSUserDefaults.standardUserDefaults()
userDefaults.setObject(person, forKey: "personInfo")
userDefaults.synchronize()
but I it is wrong, what is the right way to set a class instance to userDefaults ?
Thanks for your answers,
Best regards

Answer 1

As per NSUserDefaults Class Reference:
The value parameter can be only property list objects: NSData, NSString, NSNumber, NSDate, NSArray, or NSDictionary. For NSArray and NSDictionary objects, their contents must be property list objects.
You need to serialize your Person instance into one of those objects before saving it into the user defaults.
One of many ways to do it is to implement NSCoding protocol in your class:
class Person: NSCoding {
required init(coder aDecoder: NSCoder) {
self.id = aDecoder.decodeIntegerForKey("id")
self.name = aDecoder.decodeStringForKey("name")
self.email = aDecoder.decodeStringForKey("email")
}
func encodeWithCoder(aCoder: NSCoder) {
aCoder.encodeInteger(self.id, forKey: "id")
aCoder.encodeString(self.name, forKey: "name")
aCoder.encodeString(self.email, forKey: "email")
}
}
// when writing your defaults...
let personData = NSKeyedArchiver.archivedDataWithRootObject(person)
userDefaults.setObject(personData, forKey: "personInfo")
// then, when reading your defaults...
let personData = userDefaults.objectForKey("personInfo") as NSData?
if let personData = personData? {
let person = NSKeyedUnarchiver.unarchiveObjectWithData(personData) as Person
}
Alternatively, you can just save your personJSON dictionary to the defaults.