Expose more MGLMapViewDelegate methods

[frederoni]

We only delegate mapView(_:viewFor:) and mapView(_:imageFor:) to the NavigationViewControllerDelegate currently. Let's add a few more requested (#666) delegate methods.

• mapView(_:regionWillChangeAnimated:)
• mapView(_:regionDidChangeAnimated:)

• mapView(_:didFinishLoading:) (both methods)
• mapView(_:viewForAnnotation:)
• mapView(_:didAddAnnotationViews:)
• mapView(_:annotationCanShowCallout:)
• mapView(_:tapOnCalloutForAnnotation:)

@bsudekum @1ec5

[1ec5]

NavigationMapView currently seems to implement only mapView(_:imageFor:) and mapView(_:viewFor:), and it does so by turning around and ultimately asking the NavigationViewControllerDelegate’s implementation of those methods. So does NavigationMapViewController even need to be NavigationMapView’s delegate? If not, we can remove all these pass-throughs and let the developer set the map view’s delegate to their own view controller.

[frederoni]

@1ec5 It would be great if we could expose all of MGLMapViewDelegate but the RouteMapViewController needs mapView:didFinishLoadingStyle: and mapView:regionDidChangeAnimated:. 🤔

[1ec5]

We could imitate -mapView:didFinishLoadingStyle: by key-value observing the style key path. We could move RouteMapViewController off -mapView:regionDidChangeAnimated: using didSet handlers on various properties like tracksUserCourse.

[akitchen]

see also #1526

[1ec5]

Edited the original post with some more MGLMapViewDelegates that developers have told us they’d like to see exposed through NavigationMapViewDelegate and/or NavigationViewControllerDelegate.

[akitchen]

Is there a reason why we don't offer message passing of the entire MGLMapViewDelegate family of delegate methods? Are there any which would negatively impact the navigation experience or be otherwise disruptive?

[1ec5]

Passing the entire public interface of MGLMapViewDelegate is the most straightforward solution. The downsides would be that NavigationViewControllerDelegate becomes even more bloated and that we still rely on manually plumbing delegate methods through both RouteMapViewController and NavigationViewController as they’re added to the map SDK. (We’ll need to keep a close eye on the map SDK for any such additions.)

We could expose RouteMapViewController publicly as the go-to class for customizing the map view that’s embedded in NavigationViewController, removing one level of indirection. But there will still be the same issue of NavigationViewController hogging access to the RouteMapViewController’s delegate methods.