消除循环依赖并创建对象

我的解决方案中有三个项目

• ClassLibrary=>引用接口库，UIProject包含（CountDownTimer.cs）

• 界面库包含（ICountDownTimer.cs）

• UIProject=>引用接口库包含（frmMain.cs，Controller.cs）

我读到添加接口是消除循环依赖的一种方法，我试图找到解决问题的方法，但一直没有找到。

我需要在控制器类中创建一个新的CountDownTimer对象，任何人都可以建议或帮助吗

public partial class frmMain : Form
{
    //Reference to the Controller class, so we can call it
    private Controller MController { get; set; }
    //Constructor
    public frmMain(Controller cntr)
    {
        MController = cntr;
        InitializeComponent();
    }
    private void frmMain_FormClosed(object sender, FormClosedEventArgs e)
    {
        //Because controller is the main class, closing the form won't exit the program
        //So we need to close it with an exit call
        Application.Exit();
    }
    private void btn_Start_Click(object sender, EventArgs e)
    {
        MController.StartTimer();
    }
}

public class Controller : ApplicationContext
{
    //Store a reference to the UI
    internal frmMain MainUI { get; set;}
    private ICountDownTimer timer;
    public Controller()
    {
        MainUI = new frmMain(this);
        MainUI.Show();
    }
    internal void StartTimer()
    {
    }
}
public class CountDownTimer : ICountDownTimer
    {
        private int seconds; // Time in seconds
        private int reSetValue; // Time in seconds
        private System.Windows.Forms.Timer timer1;
        private Controller parent;
        public CountDownTimer(Controller parent, int seconds)
        {
            this.parent = parent;
            this.seconds = seconds;
            reSetValue = seconds;
            timer1 = new System.Windows.Forms.Timer();
            timer1.Tick += new EventHandler(timer1_Tick); // Add Handler(timer1_Tick)
            timer1.Interval = 1000; // 1 second
            //parent.TickUpdate(("" + seconds / 60).PadLeft(2, '0') + "m:" + ("" + seconds % 60).PadLeft(2, '0') + "s");
        }
        private void timer1_Tick(object sender, EventArgs e)
        {
            seconds--; // Decrement seconds
            if (seconds == 0) // Stop Timer at 0
            {
                timer1.Stop(); // Stop timer
            }
            else
            {
                //parent.TickUpdate(convertSecondToMMSS());
                if (seconds % 60 == 0 || seconds >= 1 && seconds <= 10)
                {
                    //parent.TickUpdate(seconds);
                }
            }
        }
        void ICountDownTimer.StartTimer()
        {
            timer1.Start(); // Start Timer
        }
        public string convertSecondToMMSS()
        {
            TimeSpan t = TimeSpan.FromSeconds(seconds);
            string str = string.Format("{0:D2}m:{1:D2}s",
                t.Minutes,
                t.Seconds);
            return str;
        }
        void ICountDownTimer.StopTimer()
        {
            timer1.Stop();
        }
        void ICountDownTimer.ResetTimer()
        {
            timer1.Stop();
            seconds = reSetValue;
            //parent.TickUpdate(convertSecondToMMSS());
        }
        void ICountDownTimer.SetTimer(int seconds)
        {
            timer1.Stop();
            this.seconds = seconds;
            reSetValue = seconds;
            //parent.TickUpdate(convertSecondToMMSS());
        }
    }
public interface ICountDownTimer
{
    void StartTimer();
    void StopTimer();
    void ResetTimer();
    void SetTimer(int seconds);
}