AppDelegate.swift に次の行を追加してみてください。
static let kAppDidBecomeActive = "kAppDidBecomeActive"
static let kAppWillResignActive = "kAppWillResignActive"
func applicationDidBecomeActive(application: UIApplication) {
// Your application is now the active one
// Take into account that this method will be called when your application is launched and your timer may not initialized yet
NSNotificationCenter.defaultCenter().postNotificationName("kAppDidBecomeActive", object: nil)
}
func applicationWillResignActive(application: UIApplication) {
// Home button is pressed twice
NSNotificationCenter.defaultCenter().postNotificationName("kAppWillResignActive", object: nil)
}
さらに、View Controller をこれらの通知のオブザーバーとして設定します。
override func viewDidLoad() {
super.viewDidLoad()
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(pauseGame), name: AppDelegate.kAppWillResignActive, object: nil)
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(resumeGame), name: AppDelegate.AppDelegate.kAppDidBecomeActive, object: nil)
}