How to run a timer in background in xamarin forms? - xamarin

Question

In my app I want to set a timer to calculate the working time. My timer is working fine but when I switch to another page then it stops working. How to run the timer and calculate total time run in the background. Here is my code
Stopwatch st = new Stopwatch();
private void WorkClockStart(object sender,EventArgs e)
{
if(LaborClock.Text == "Start Work Clock")
{
LaborClock.Text = "Stop Work Clock";
Device.StartTimer(TimeSpan.FromMilliseconds(1), () =>
{
st.Start();
return false;
});
}
else
{
st.Stop();
long elapsed = st.ElapsedMilliseconds;
var sec = elapsed / 1000;
DisplayAlert("Message", "Worked Time(Sec): " + sec, "ok");
LaborClock.Text = "Start Work Clock";
st.Reset();
}
}
How to achieve this in Xamarin.Forms?

Answer 1

Why do you use a timer? Just store the DateTime.Now in a variable when you start your watch and compute the delta with DateTime.Now when you stop it.
Then you can store wherever you want (in a static variable for example or in App.cs if you want depending on your requirement)

Answer 2

I agree with Daniel you can use DateTime and Task.Factory.StartNew, Like the below code.
Task.Factory.StartNew( async() =>
{
var time = DateTime.Now;
var counter = 30;
transactionItem.RetryCount = 30;
do
{
await Task.Delay(1000);
counter = Math.Abs((DateTime.Now - time.AddSeconds(29)).Seconds);
} while (counter != 0 && time.AddSeconds(29) > DateTime.Now);
});