Question

I’m familiar with the control’s dispatcher object but that doesn’t solve my issue in an MVVM scenario.

I’ve got a UI command, that calls a method on my VM, that spawns a thread and then returns, when the thread is done (background worker might be good for this?) it will raise a callback, but the trick is, that callback modifies an observable collection, so how can I raise this callback on the UI thread?

Answer 1

Use the Dispatcher associated with the UI thread. Normally you would have a base ViewModel class that exposes the Dispatcher to all subclasses. Then your VM would do something like:

Dispatcher.Invoke((ThreadStart) delegate
{
    //this code executes on the UI thread
});