How to Call a method in UI thread from another running thread in UWP?

Question

I want to call Update(int i) from inside of the Thread. I used to use BeginInvoke(), but it isn't available in UWP.

public class Viewmodel
{
 Viewmodel()
 {
   //start task
   var mainTask = Task.Factory.StartNew(() =>
   {
     MyThread();
   });
 }
 private void MyThread()
 {
    int i;
    while(condition)
    {
      //do somethings
      Update(i) 
    }
 }
 private Update(int i)
 {
   //do somethings
 }
}

score 2 · Accepted Answer · answered Jul 16 '17 at 14:03

2

The below should work.

Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
() =>
{
    // update your UI here
    Update(i) 
});

answered Jul 16 '17 at 14:03

thunderbird

2,715
5
27
51

Since the original question mentioned running in a view-model class, you could use `this.Dispatcher` instead. Relying on `MainView` will cause breaks if the app ever has more than one view. – Peter Torr - MSFT Jul 16 '17 at 15:41
Where would I use this code, inside Task when I would want to call `Update()`? – Amir Hussein Nargesian Jul 16 '17 at 19:30
@AmirHusseinNargesian you can just put this inside Update() function and add your logic within the Dispatch handler. – thunderbird Jul 17 '17 at 07:04

lindexi · Answer 2 · 2017-07-18T12:34:00.660

-1

You can use the below code to run your code :

await Window.Current.Dispatcher.RunAsync(CoreDispatcherPriority.High/* the rank */,
() =>
{
    // run the code
});

And I have another way to do it

  await CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal /*the rank*/, () => { // run the code  });

See https://stackoverflow.com/a/38175976/6116637

edited Jul 18 '17 at 12:34

answered Jul 16 '17 at 14:10

lindexi

4,182
3
19
65

1

[The documentation](https://learn.microsoft.com/en-us/uwp/api/Windows.UI.Core.CoreDispatcherPriority) clearly says not to use the value `High`. – Peter Torr - MSFT Jul 16 '17 at 15:27
@PeterTorr-MSFT Thx, but I want to say you can set the rank in this. – lindexi Jul 17 '17 at 03:14

How to Call a method in UI thread from another running thread in UWP?

2 Answers2