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@rileytestut
Created December 7, 2015 03:30
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//: Playground - noun: a place where people can play
import Foundation
enum GameSystemIdentifier
{
case Wii
case Xbox
case PlayStation
}
struct Game
{
let name: String
let URL: NSURL
let gameSystemIdentifier: GameSystemIdentifier
}
// Abstract class
// Handles receiving a Game struct, and then can "play" the game
// Because each system is different, there are specialized subclasses intended to each handle a specific system
class GameSystem
{
// This method is invoked whenever GameSystem(game: game) is called to determine what subclass should be initialized
// The return type should (theoretically) be of type GameSystem.Type, but alas that is currently a compile-time error
class func dynamicTypeForInitializationParameters(parameters: [String: AnyObject]) -> AnyObject.Type /* GameSystem.Type */
{
// The `parameters` dictionary maps strings representing the initializer parameter names to the provided values
// In this case, "game" maps to an instance of Game
guard let game = parameters["game"] as? Game else { return GameSystem.self }
switch game.gameSystemIdentifier
{
case .Wii: return WiiGameSystem.self
case .Xbox: return XboxGameSystem.self
case .PlayStation: return PlaystationGameSystem.self
}
}
init(game: Game)
{
// Initialize as normal
}
}
// "Private" implementation subclasses, specialized for handling games made for that specific system
class WiiGameSystem { }
class XboxGameSystem { }
class PlaystationGameSystem { }
// In practice, the gameSystemIdentifier would be determined dynamically by reading the UTI of the file at URL
let game = Game(name: "Pokemon", URL: NSURL(string: "path/to/game")!, gameSystemIdentifier: .Wii)
// Caller has no need to know exactly what GameSystem will be used to run the game
// This is great if the framework separates each GameSystem into a separate module, and could add more later on
let gameSystem = GameSystem(game: game)
// In theory, this would print "WiiGameSystem"
print(gameSystem.dynamicType)
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