Using enum as property of Realm model

Question

Is it possible to use an Enum as a property for my model? I currently have a class like this:

class Checkin: RLMObject {
  dynamic var id: Int = 0
  dynamic var kind: String = "checked_in"
  var kindEnum: Kind = .CheckedIn {
    willSet { self.kind = newValue.rawValue }
  }

  enum Kind: String {
    case CheckedIn = "checked_in"
    case EnRoute = "en_route"
    case DroppedOff = "dropped_off"
  }
  ....
}

It works okay, but I'd like to be able to have the kind property be the Enum and have Realm automatically call .rawValue on the property when it is saving an object to the store. Is this possible in Realm or is there a feature request already out there for it?

Answer 1

You should override your kindEnum's setter and getter for this case:

enum Kind: String {
  case CheckedIn
  case EnRoute
  case DroppedOff
}

class Checkin: Object {
  @objc dynamic var id = 0
  var kind = Kind.CheckedIn.rawValue
  var kindEnum: Kind {
    get {
      return Kind(rawValue: kind)!
    }
    set {
      kind = newValue.rawValue
    }
  }
}

Answer 2

I've refined this model a little further.

enum Thing: String {
    case Thing1
    case Thing2
    case Thing3
}

then in my Realm class object:

class myClass : Object {
    private dynamic var privateThing = Thing.Thing1.rawValue
    var thing: Thing {
        get { return Thing(rawValue: privateThing)! }
        set { privateThing = newValue.rawValue }
    }
}

This allows us to write

myClassInstance.thing = .Thing1

(storing "Thing1" into privateThing), but prevents typing of

myClassInstance.privateThing = "Thing4"

which is not a valid value so preserving data integrity.

Answer 3

Since Realm support Objective-C enums and they are representable by Int you can use this:

class Checkin: Object {
  dynamic var id: Int = 0
  dynamic var kind: Kind = .checkedIn

  @objc enum Kind: Int {
    case checkedIn
    case enRoute
    case droppedOff
  }
  ....
}

If you need to parse to/from String you can use a custom initializer for Kind and an toString function.

There is a discussion about this in GitHub

This works with Swift 3.0 and Realm 2.0.2