How can I save the previous state in a way that allows it to be entered again with GKStateMachine?

Question

I am using GKStateMachine to keep track of the state of tiles in my game.

When I place an item, the tiles that are covered by the item are put into a "planned" state. How can I store and then return the tiles to the previous state at a later point?

Here are the parts of the code I figure are relevent to my question. Happy to share more on specific requests.

//...
// Have previously entered the tiles stored in the global Game object into a state which is not "planned" state
  class func movePlannedObject(x: Int, y: Int) {

    //DO Some things

    for tile in Game.sharedInstance.plannedBuildingTiles {
      tile.stateMachine.enterState(tile.previousState!)
    }

    // Set new position and change state of tiles to planned

  }

//...

And the state machine:

class TileState : GKState{

  var tile : Tile?

  init( tile: Tile ) {
    super.init()
    self.tile = tile
  }
}


class TileTileState: TileState {
}

class TileGrassState: TileState {
}

class TilePathState: TileState {
}

class TilePlanState: TileState {

  override func didEnterWithPreviousState(previousState: GKState?) {
    super.didEnterWithPreviousState(previousState)

    tile?.previousState = // What?
    print(tile?.previousState)

    Game.sharedInstance.plannedBuildingTiles.append(tile!)
  }

}

Gist: https://gist.github.com/Relequestual/dac6d51c923e5ce4224e

If I set previousState to previousState, I cannot then enter the state using that vairable...

// In the tile class
var previousState: GKState?

// In states function didEnterWithPreviousState
tile?.previousState = previousState

// Elsewhere
tile.stateMachine.enterState(tile.previousState!)

Compile time error:

Cannot convert value of type 'GKState' to expected argument type 'AnyClass' (aka 'AnyObject.Type')

Answer 1

In case this question is not answered yet, this could be one solution : swift :

Declare a var in your main game class:

var previousState: AnyClass?

GKState class has a willExit function, in this function you can define this var, because this same class is going to be the previous state :

override func willExit(to nextState: GKState) {

    self....?.previousState = ThisClassState.self
}

Then in your main game class, you can call this var :

self.myGameStateMachine?.enter(self.previousState)

I hope this is enough clear to make you go on.

Answer 2

Create property in your scene or StateClass

var previousState: GKState?

Update property in your GKStates didEnter method

override func didEnter(from previousState: GKState?) {
    super.didEnter(from: previousState)
    self.previousState = previousState
}

And to use it call

if let previousState = previousState {
    stateMachine.enter(type(of: previousState))
}