Create Behavior from Map Property in Control - Xamarin Forms MVVM Prism ArcGIS - xamarin

Question

I'm trying to show a callout when navigating from View A (form view) to View B (map view). I pass the record detail for the callout from View A to View B and it's bound to viewmodel of View B.
I would like to access the LoadStatusChanged event on the Map property of the Esri MapView control while adhering to MVVM architecture. Here is what my control looks like:
<esri:MapView x:Name="mapViewMain"
Map="{Binding MainMap}"
Grid.Row="0"
InteractionOptions="{Binding MapViewOptions}"
GraphicsOverlays="{Binding GraphicsOverlays}">
<esri:MapView.Behaviors>
<bh:ShowCalloutOnTapBehavior CalloutClickCommand="{Binding GoToDetailCommand}" />
<bh:ShowCalloutOnDataReceivedBehavior MeterMasterRequest="{Binding RequestParameters}" Map="{Binding MainMap}" />
</esri:MapView.Behaviors>
</esri:MapView>
I think I need to create a behavior that will take in the Map, wait for it to finish load, then show callout (results of MeterMasterRequest) on MapView (the ShowCallout method is on MapView control).
public class ShowCalloutOnDataReceivedBehavior : BehaviorBase<MapView>
{
public static readonly BindableProperty MeterMasterRequestProperty =
BindableProperty.Create(nameof(MeterMasterRequest), typeof(MeterMasterRequest), typeof(ShowCalloutOnDataReceivedBehavior));
public static readonly BindableProperty MapProperty =
BindableProperty.Create(nameof(Map), typeof(Map), typeof(ShowCalloutOnDataReceivedBehavior));
public MeterMasterRequest MeterMasterRequest
{
get { return (MeterMasterRequest)GetValue(MeterMasterRequestProperty); }
set { SetValue(MeterMasterRequestProperty, value); }
}
public Map Map
{
get { return (Map)GetValue(MapProperty); }
set { SetValue(MapProperty, value); }
}
How can I bind to the Map event from here? I don't know how I can get BehaviorBase to be of type Map. I seem to only be able to set behaviors at MapView level.

Answer 1

You can access the Map from the MapView.Map property and the MapView is passed in to the OnAttachedTo and OnDetachingFrom methods of the Behavior class. I see you have a BehaviorBase, which hopefully has the OnAttachedTo and OnDetachingFrom overrides still marked as protected virtual so you can override them in your ShowCalloutOnDataReceivedBehavior class
Override the OnAttachedTo method and then subscribe to the LoadStatusChanged event, override OnDetachingFrom so you can unsubscribe like so:
protected override void OnAttachedTo(MapView bindable)
{
base.OnAttachedTo(bindable);
bindable.Map.LoadStatusChanged += Map_LoadStatusChanged;
}
protected override void OnDetachingFrom(MapView bindable)
{
base.OnDetachingFrom(bindable);
bindable.Map.LoadStatusChanged -= Map_LoadStatusChanged;
}
private void Map_LoadStatusChanged(object sender, Esri.ArcGISRuntime.LoadStatusEventArgs e)
{
// Do stuff when LoadStatusChanged event is fired on the Map
}