通话期间暂停游戏，接听电话和按主页按钮之间的区别？

Question

按下主页按钮后，我的游戏暂停。但是当我接到电话时却没有。当游戏变为活动状态时，其动作将恢复。我没有得到一个电话和按HB之间的区别。请帮帮我。

感谢。

func pauseGame(){

    initResumeButton()
    pause.removeFromParent()

    gamePaused = true
    self.paused = true
}

func resumeGame(){
    resume.removeFromParent()
    initPauseButton()

    gamePaused = false
    self.paused = false
}

func registerAppTransitionObservers(){
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "applicationWillResignActive", name: UIApplicationWillResignActiveNotification, object: nil)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "applicationDidEnterBackground", name: UIApplicationDidEnterBackgroundNotification, object: nil)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "applicationWillEnterForeground", name: UIApplicationWillEnterForegroundNotification, object: nil)
}

func applicationWillResignActive(){

    if !gamePaused && state != .GameStarting{
        pauseGame()
    }

}

func applicationDidEnterBackground(){
    self.view?.paused = true
}

func applicationWillEnterForeground(){
    self.view?.paused = false  
    if gamePaused{
        self.paused = true
   }
}