Xamarin PCL缺少System.Timer

Question

我正在使用.Net 4.5.1构建一个针对IOS Android和Windows Phone 8.1的Xamarin跨平台应用程序.当我尝试在PCL项目中引用System.Timers时,它不存在.我该如何解决？

Answer 1

您可以使用:Device.StartTimer

句法 :

public static void StartTimer (TimeSpan interval, Func<bool> callback)

示例:每1秒递增1分钟

int number = 0;
Device.StartTimer(TimeSpan.FromSeconds(1),() => {
    number++;
    if(number <= 60) 
    {
        return true; //continue
    }
    return false ; //not continue

});

示例:等待5秒钟以运行一次功能

Device.StartTimer(TimeSpan.FromSeconds(5),() => {
    DoSomething();
    return false ; //not continue
});

Answer 2

前几天我注意到了这一点.虽然这个类是在API文档System.Threading.Timer Class ..Annoying.

无论如何,我创建了自己的Timer类,使用Task.Delay():

public class Timer
{

        private int _waitTime;
        public int WaitTime
        {
            get { return _waitTime; }
            set { _waitTime = value; }
        }

        private bool _isRunning;
        public bool IsRunning
        {
            get { return _isRunning; }
            set { _isRunning = value; }
        }

        public event EventHandler Elapsed;
        protected virtual void OnTimerElapsed()
        {
            if (Elapsed != null)
            {
                Elapsed(this, new EventArgs());
            }
        }

        public Timer(int waitTime)
        {
            WaitTime = waitTime;
        }

        public async Task Start()
        {
            int seconds = 0;
            IsRunning = true;
            while (IsRunning)
            {
                if (seconds != 0 && seconds % WaitTime == 0)
                {
                    OnTimerElapsed();
                }
                await Task.Delay(1000);
                seconds++;
            }
        }

        public void Stop()
        {
            IsRunning = false;
        }
}