NSCodingExample.swift

class Person: NSObject, NSCoding {
    
    
    var firstName: String
    var lastName: String
    
    override var description: String {
        return self.firstName + " " + self.lastName
    }
    
    init(firstName: String, lastName: String) {
        self.firstName = firstName
        self.lastName = lastName
        
        super.init()
    }
    
    func encode(with aCoder: NSCoder) {
        aCoder.encode(self.lastName, forKey: "last")
        aCoder.encode(self.firstName, forKey: "first")
    }
    
    required init?(coder aDecoder: NSCoder) {
        self.lastName = aDecoder.decodeObject(forKey: "last") as! String
        self.firstName = aDecoder.decodeObject(forKey: "first") as! String
        
        super.init()
    }
}


///  Save to file
let moi = Person(firstName: "Matt", lastName: "Neuburg")

if let moifile = try? FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: false).appendingPathComponent("moi.txt"){

    do {
        let moidata = NSKeyedArchiver.archivedData(withRootObject: moi)
        try moidata.write(to: moifile)
        print(moifile)
        print("saved data successfully")
    } catch let error {
        print("couldn't save \(error)")
    }
}


/// Read from file

if let moifile = try? FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: false).appendingPathComponent("moi.txt"){
    
    do {
    let persondata = try Data(contentsOf: moifile)
    let person = NSKeyedUnarchiver.unarchiveObject(with: persondata) as! Person
    print(person)
    } catch let error {
        print("couldn't save \(error)")

    }
}