Swift 3 which is the best way to store of an Object with array etc - swift

Question

I started to develop with Swift 3 and i´m getting crazy. Following Situation:
class subObject
{
var name : String
var list : [Int]
init( _name : String, _list : [Int] ){
self.name = _name
self.list = _list
}
}
class mainObject
{
var subObjectList : [subObject]
init( _list : [subObject] ){
self.subObjectList = _list
}
}
var data : [mainObject]
Which way is state of the art to store var data : [mainObject] persistently. I've already unsuccessfully tried .plistand NSKeyedArchiver.
Sorry but my english is worse.

Answer 1

NSCoding cannot be used because the classes aren't subclasses of NSObject.
Since all properties in both classes are property list compliant you could add a computed property propertyListRepresentation and an appropriate initializer.
Class names are supposed to start with a capital letter and parameters starting with an underscore are unusual in Swift.
class SubObject
{
var name : String
var list : [Int]
init(name : String, list : [Int] ){
self.name = name
self.list = list
}
init?(dictionary : [String:Any]) {
guard let name = dictionary["name"] as? String,
let list = dictionary["list"] as? [Int] else { return nil }
self.name = name
self.list = list
}
var propertyListRepresentation : [String:Any] {
return ["name" : name, "list" : list]
}
}
class MainObject
{
var subObjectList : [SubObject]
init(list : [SubObject] ){
self.subObjectList = list
}
init(propertyList : [[String:Any]] ){
self.subObjectList = propertyList.flatMap{ SubObject(dictionary: $0) }
}
var propertyListRepresentation : [[String:Any]] {
return subObjectList.map{ $0.propertyListRepresentation }
}
}
To use it:
let subs = [SubObject(name: "Foo", list: [1, 2, 3]), SubObject(name: "Bar", list: [4, 5, 6])]
let main = MainObject(list: subs)
let list = main.propertyListRepresentation
let data = try! PropertyListSerialization.data(fromPropertyList: list, format: .xml, options: 0)
print(String(data:data, encoding: .utf8)!)
let restoredList = try! PropertyListSerialization.propertyList(from: data, format: nil) as! [[String:Any]]
let restoredMain = MainObject(propertyList: restoredList)