Delay region-related delegate methods until after map view has loaded

[jmkiley]

-mapView:regionDidChangeAnimated: and -mapViewRegionIsChanging: (for example) can be called before the map view has finished loading. We may want to explore ways to prevent these methods from being called until after the map view has finished loading.

cc @boundsj

[boundsj]

I think that, currently, the region change delegate methods get called in response to application code setting the camera or the MGLMapView itself doing its initial camera setup. There is currently nothing that enforces any order of these calls and there is no mechanism to queue camera related calls until after the style / map has finished loading.

[1ec5]

Does MapKit avoid calling -mapView:regionDidChangeAnimated: until after -mapViewDidFinishLoadingMap:?

[friedbunny]

Does MapKit avoid calling -mapView:regionDidChangeAnimated: until after -mapViewDidFinishLoadingMap:?

No, MapKit can call -mapView:regionDidChangeAnimated: before -mapViewWillStartRenderingMap: and -mapViewWillStartLoadingMap:, so our current behavior is consistent.

We should probably keep reenforcing to developers that they should avoid using -mapView:regionDidChangeAnimated: for anything that requires a fully-loaded map — or that they’ll need to keep track of if the map has finished loading themselves.

Relatedly: #2775 covers ways we are inconsistent with MapKit.

[stale]

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