Gameloop in Swift

GameLoop.swift

import UIKit

class GameLoop : NSObject {
    
    var doSomething: () -> ()!
    var displayLink : CADisplayLink!
    var frameInterval : Int!

    init(frameInterval: Int, doSomething: () -> ()) {
        self.doSomething = doSomething
        self.frameInterval = frameInterval
        super.init()
        start()
    }

    // you could overwrite this too
    func handleTimer() {
        doSomething()
    }
    
    func start() {
        displayLink = CADisplayLink(target: self, selector: Selector("handleTimer"))
        displayLink.frameInterval = frameInterval
        displayLink.addToRunLoop(NSRunLoop.mainRunLoop(), forMode: NSRunLoopCommonModes)
    }

    func stop() {
        displayLink.removeFromRunLoop(NSRunLoop.mainRunLoop(), forMode: NSDefaultRunLoopMode)
        displayLink = nil
    }
}