Question

我正在Xamarin开发应用程序，它正在跟踪手机上用户的当前位置。

当我在模拟器上测试应用程序时它没有任何问题，当我在手机应用程序上部署它工作10秒钟时，我可以看到顶部有GPS图标闪烁。 5秒钟后，GPS图标停止闪烁，应用程序崩溃与＃34;不幸的是MyApp已经停止＆＃34;。

如何在手机上调试，因为它可以在模拟器上运行？我认为这是一些线程问题。

得到堆栈跟踪，SIGSEGV致命错误： http://pastebin.com/Bxt68ikj

我的代码：
的 Timer.cs

 public delegate void TimerCallback(object state);

    public sealed class Timer : CancellationTokenSource, IDisposable
    {
        public int DueTime { get; set; }
        public int Period { get; set; }

        public void Start(TimerCallback callback, object state)
        {
            Task.Delay(DueTime, Token).ContinueWith(async (t, s) =>
            {
                var tuple = (Tuple<TimerCallback, object>)s;

                while (true)
                {
                    if (IsCancellationRequested)
                        break;
                    Task.Run(() => tuple.Item1(tuple.Item2));
                    await Task.Delay(Period);
                }

            }, Tuple.Create(callback, state), CancellationToken.None,
               TaskContinuationOptions.ExecuteSynchronously | TaskContinuationOptions.OnlyOnRanToCompletion,
               TaskScheduler.Default);
        }

        public new void Dispose() { base.Cancel(); }
    }

TimerLocationService.cs

public class TimerLocationService : ITimerLocationService
{
    private Timer _timer;

    public void Start(TimerCallback callback, object state)
    {
        _timer = new Timer();
        _timer.DueTime = 60000;
        _timer.Period = 60000;
        _timer.Start(callback, null);
    }

    public void SetTimer(int dueTime, int period)
    {
        _timer.DueTime = dueTime;
        _timer.Period = period;
    }

    public void Dispose()
    {
        _timer.Dispose();
    }
}

MainPageViewModel.cs

public class MainPageViewModel : ViewModelBase
    {
        private readonly IAccountService _accountService;
        private readonly IGeolocatorService _geolocatorService;
        private readonly ITimerLocationService _timerLocationService;

        public MainPageViewModel(IAccountService accountService, IGeolocatorService geolocatorService, ITimerLocationService timerLocationService)
        {
            _accountService = accountService;
            _geolocatorService = geolocatorService;
            _timerLocationService = timerLocationService;
            LabelUsername = GetUsername();
            GetCurrentCoordinates();
            _timerLocationService.Start(SendCoordinates, null);
        }

        private string _logoutButtonText = "Login";

        public string LogoutButtonText
        {
            get { return _logoutButtonText; }
            set
            {
                _logoutButtonText = value;
                RaisePropertyChanged();
            }
        }

        private string _labelUsername = "Login";

        public string LabelUsername
        {
            get { return _labelUsername; }
            set
            {
                _labelUsername = value;
                RaisePropertyChanged();
            }
        }

        private string _labelCoordinate = "0";
        public string LabelCoordinate
        {
            get { return _labelCoordinate; }
            set
            {
                _labelCoordinate = value;
                RaisePropertyChanged();
            }
        }

        public ICommand LogoutCommand => new MethodInvokerCommand(Logout);
        public ICommand TimerCommand => new MethodInvokerCommand(SetTimer);

        private void SetTimer()
        {
            _timerLocationService.SetTimer(10000, 10000);
        }

        private void Logout()
        {
            _accountService.Logout();
        }

        private string GetUsername()
        {
            return _accountService.GetUsername();
        }

        private async void GetCurrentCoordinates()
        {
            var position = await _geolocatorService.GetPositionAsync();

            LabelCoordinate = position.Latitude + ", " + position.Longitude;

            await _geolocatorService.SendPositionAsync();
        }

        private async void SendCoordinates(object args)
        {
            await _geolocatorService.SendPositionAsync();
        }
    }

Answer 1

为什么你有一个计时器......一点都没有？

您可以订阅位置更改时引发的事件，并对此作出反应。通过这样的计时器进行轮询就是1990年代。

如何调试不幸MyApp已经停止了？适用于模拟器，而不是电话

1 个答案: