black square before map render

[incanus]

Haven't been able to confirm on Android yet, but I see this almost every time on iOS.

Just before the map appears, a black square smaller than the map view shows up.

[tobrun]

Verified that I'm not seeing this on Android.
Start up frame-by-frame:

idk but could be related to drawing before setting up the view correctly (related to glViewport or mbgl::Update::Dimensions?).

[friedbunny]

My guess is that this has to do with the storyboard initialization.

[friedbunny]

Setting MGLMapView.opaque = NO fixes the initial black flash — indeed, this issue (#3101) was the impetus for implementing opaque.

One idea I bounced off of @1ec5 was to set opaque = NO until mapDidFinishLoading fires, but that would have likely performance implications and complicate the situation where developers wanted to keep opaque = NO enabled themselves.

[friedbunny]

Fixed in #7859 for most use cases.