converting custom object to NSData Swift - ios

Question

I have been researching all over the interweb, especially Stack overflow, and my own references I have at home, but I have not been able to figure out what is wrong with my code. I have spent most of my day trying to figure this issue out, and I hope somebody here can help point me in the correct direction.
Setup:
I have a chess app that I am building in Swift 3.0, and the structure is as follows: BoardModel is the class that holds all of the data about the game, Piece is a class within board model which holds data about itself within the BoardModel, Piece also has a PieceType enum for .knight, .king, etc.
The BoardModel has a 2D array of Piece representing the chess board. Now, with each move, I want to save the game data in Game Center, but before I can even try to store the game data, the encoding throws an error and that is where I am. The error just points at AppDelegate with the statement: "Thread: 1 signal SIGABRT".
Here is the code that is the problem along with the Piece class:
let pieceData = NSKeyedArchiver.archivedData(withRootObject: board.board[0][0]) // where the error is thrown
class Piece: NSObject, NSCoding {
var isSelected: Bool
var type: PieceType
var isWhite: Bool
var isFirstMove: Bool
var symbol: String!
var position: (row: Int, col: Int)!
override init() {
isSelected = false
type = PieceType.empty
isWhite = true
isFirstMove = true
}
required init(coder aDecoder: NSCoder) {
isSelected = aDecoder.decodeBool(forKey: "isSelected")
type = aDecoder.decodeObject(forKey: "type") as! BoardModel.PieceType
isWhite = aDecoder.decodeBool(forKey: "isWhite")
isFirstMove = aDecoder.decodeBool(forKey: "isFirstMove")
symbol = aDecoder.decodeObject(forKey: "symbol") as! String
position = aDecoder.decodeObject(forKey: "position") as! (Int, Int)
}
func encode(with aCoder: NSCoder) {
aCoder.encode(isSelected, forKey: "isSelected")
aCoder.encode(type, forKey: "type")
aCoder.encode(isWhite, forKey: "isWhite")
aCoder.encode(isFirstMove, forKey: "isFirstMove")
aCoder.encode(symbol, forKey: "symbol")
aCoder.encode(position, forKey: "position")
}
init(isSelected: Bool, type: PieceType, isWhite: Bool, isFirstMove: Bool, symbol: String, position: (Int, Int)) {
self.isSelected = isSelected
self.type = type
self.isWhite = isWhite
self.isFirstMove = isFirstMove
self.symbol = symbol
self.position = position
}
func setPosition(to newPosition: (row: Int, col: Int)) {
position = newPosition
}
}

Answer 1

if your Enum is like this PieceType and type is Int
enum PieceType : Int {
case empty
case notEmpty
}
Then write encode and decode method like this way
required init(coder aDecoder: NSCoder) {
isSelected = aDecoder.decodeBool(forKey: "isSelected")
type = PieceType(rawValue: aDecoder.decodeObject(forKey: "type") as! Int)!
isWhite = aDecoder.decodeBool(forKey: "isWhite")
isFirstMove = aDecoder.decodeBool(forKey: "isFirstMove")
symbol = aDecoder.decodeObject(forKey: "symbol") as! String
position = aDecoder.decodeObject(forKey: "position") as! (Int, Int)
}
func encode(with aCoder: NSCoder) {
aCoder.encode(isSelected, forKey: "isSelected")
aCoder.encode(type.rawValue, forKey: "type")
aCoder.encode(isWhite, forKey: "isWhite")
aCoder.encode(isFirstMove, forKey: "isFirstMove")
aCoder.encode(symbol, forKey: "symbol")
aCoder.encode(position.row, forKey: "position.row")
aCoder.encode(position.col, forKey: "position.col")
}
i have check bellow code and it work's
let pice = Piece(isSelected: true, type: .empty, isWhite: true, isFirstMove: true, symbol: "Test", position: (2, 10))
let pieceData = NSKeyedArchiver.archivedData(withRootObject:pice)
print(pieceData)
And Out put is
386 bytes