How to return a value with Dispatcher.Invoke?

Question

Anyone knows how to return a value from Dispatcher.Invoke in wpf? I want to return the selected index for a ComboBox.

Thanks!

Answer 1

int result = -1;

// this is synchronous
myCombo.Invoke(() => 
{
  result = myCombo.SelectedIndex;
});

return result;

This is, of course, kind of clunky. Better design would be to implement INotifyPropertyChanged in your VM, create a SelectedIndex property and bind the SelectedIndex property of your combo box to it. INPC binds are thread-insensitive (3.5 or 4.0+, I don't remember which), so you can read and update these properties from different threads in your VM without worry.