小编Eth*_*ler的帖子

我正在制作一个社交媒体应用程序,并且注册屏幕中的一个功能是检查用户名是否实时拍摄并放置X或检查是否已采用(再次实时).我使用计时器来完成此操作但由于某种原因,计时器在几秒钟后停止.这是怎么回事？有没有更好的方法来做这件事？

override func viewDidLoad() {
    username.delegate = self
    email.delegate = self
    password.delegate = self
    var timer = NSTimer()
    timer = NSTimer.scheduledTimerWithTimeInterval(0.01, target: self, selector: Selector("checkOrX"), userInfo: nil, repeats: true)
}

func checkOrX() {
    var query = PFQuery(className: "_User")
    query.whereKey("username", equalTo: self.username.text)
    query.findObjectsInBackgroundWithBlock { (users, error) -> Void in
        if let users = users {
            self.usernameCheck.image = UIImage(named: "X.png")
        } else {
            self.usernameCheck.image = UIImage(named: "Check.png")
        }
    }
}