c# - 标签不显示文本 - Xamarin IOS

Question

我正在做一个倒计时，应该在计数中显示一个标签，但我的 View Controller 上的标签 (lblMostrador) 不显示文本。代码是正确的，因为输出框正确显示了计数。标签工作是否有特殊配置或其他？

部分类 EsquerdaViewController : UIViewController {

    private System.Timers.Timer aTimer;
    private DateTime tempo   = new DateTime(DateTime.Now.Year, DateTime.Now.Month, DateTime.Now.Day, 0, 1, 0);
    private DateTime tempo2  = new DateTime(DateTime.Now.Year, DateTime.Now.Month, DateTime.Now.Day, 0, 0, 1);


    public EsquerdaViewController (IntPtr handle) : base (handle)
    {
    }

    public override void ViewDidLoad()
    {
        base.ViewDidLoad ();
        Console.WriteLine ("Testando...");

        btnVoltar.TouchUpInside += (sebder, e) => 
        {
            NavigationController.PopViewController(true);
        };


        btnIniciar.TouchUpInside += (sender, e) =>
        {
            aTimer = new System.Timers.Timer(1000);

            aTimer.Elapsed += OnTimedEvent;

            aTimer.AutoReset = true;

            aTimer.Enabled = true;

        };


    }

    private void OnTimedEvent(Object source, System.Timers.ElapsedEventArgs e)
    {
        System.TimeSpan diff1   = tempo.Subtract(tempo2);

        if (diff1.Minutes == 0 && diff1.Seconds == 0)
            aTimer.Stop();

        DateTime tempoNovo      = new DateTime(DateTime.Now.Year, DateTime.Now.Month, DateTime.Now.Day, 0, diff1.Minutes, diff1.Seconds);
        tempo                   = tempoNovo;
        Console.WriteLine (String.Format("{0:00}:{1:00}", diff1.Minutes, diff1.Seconds));
        lblMostrador.Text = String.Format ("{0:00}:{1:00}", diff1.Minutes, diff1.Seconds);
    }
}

Answer 1

更新 UI 对象时，需要确保在 UI 线程上执行:

InvokeOnMainThread ( () => {
  lblMostrador.Text = String.Format ("{0:00}:{1:00}", diff1.Minutes, diff1.Seconds);
});