CADisplayLink holds a strong reference to its target, forming a cycle that must be broken with -[CADisplayLink invalidate] when the animation is complete. I don’t yet have enough faith that will-change and did-change notifications are always coming from mbgl in pairs, so this change limits CADisplayLink to when MGLMapView is in the view hierarchy. It also pauses the CADisplayLink when the view is hidden or the application is in the background. Finally, -[MGLMapView invalidate] has been renamed because that term tends not to mean “redraw” in Cocoa but is rather tied to timers.
Fixes#3130.
[ios] Also invalidate CADisplayLink on removal from window
[ios] Also shut down CADisplayLink when view is hidden
Instead of exposing these methods in a private header that winds up triggering warnings publicly, just redeclare the methods in a category. Since this is a test app, we’ll catch any issues that arise from refactoring simply by testing.
Fixes#1579.
