Is It Possible To Return Data To The Previous Fragment When "fragmentmanager.popbackstack()" Is Called?

I'm developing an app with Xamarin.Android in which I have a root activity including a frame for displaying different fragments. The root activity contains only navigation items. T

Solution 1:

You should be able to pass an Action to your FilterFragment.

When OnDestroyView() is called you can invoke the Action and send back data.

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Example

First Fragment

FragmentManager.BeginTransaction()
.AddToBackStack(null)
.Replace(Resource.Id.members_filterFrame, newFilterFragment((parameter) => {
    // Do something with the given parameter
}))
.Commit();

FilterFragment

private Action<T> _onCompletionAction;
publicFilterFragment(Action<T> onCompletionAction) 
{
    _onCompletionAction = onCompletionAction;
}

publicoverridevoidOnDestroyView()
{
    base.OnResume();

    _onCompletionAction(parameter) // parameter could be a filter object.
}

Solution 2:

I solved it by firing an event with custom EventArgs after pressing the "apply filter button" in the FilterFragment:

Searched?.Invoke(this, newFilterAppliedEventArgs(FilterObject)); // fire search event
FragmentManager.PopBackStack();

The FilterAppliedEventArgs class looks like:

publicclassFilterAppliedEventArgs : EventArgs
{
    public Filter FilterObject { get; set; }

    public FilterAppliedEventArgs(Filter filter)
    {
        this.FilterObject = filter;
    }
}

And registering the event in the "User-List-Fragment" before displaying the FilterFragment like this:

var filterFragment = newFilterFragment();
// get the filter attributes
filterFragment.Searched += (s, ea) =>
{
   var eventArgs = ea asFilterAppliedEventArgs;
   LoadFilteredMembers(eventArgs.FilterObject);
};

FragmentManager.BeginTransaction()
   .AddToBackStack(null)
   .Replace(Resource.Id.members_filterFrame, filterFragment)
   .Commit();

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The approach from @Pilatus seems very handy too. Both will work and I don't know which one is the better one.