Move gesture recognizers from GLKView to TGMapView itself #2127
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If the app is still in the background during initial setup of TGMapView, the GLKView will be nil when we try to attach gesture recognizers to it - leaving us with no working gestures. To avoid this, we can instead attach the recognizers to the TGMapView itself.
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What's different?
The gesture recognizers used in
TGMapViewused to be attached to theGLKViewthat gets created as a subview. They are now attached to theTGMapViewitself. There should be no differences in behavior from this change.Why?
If the app is still in the background during initial setup of TGMapView, the GLKView will be nil when we try to attach gesture recognizers to it - leaving us with no working gestures.
To avoid this, we can instead attach the recognizers to the TGMapView itself.
This situation seems to occur in apps using the "scene" based UI framework introduced in iOS 13 (https://developer.apple.com/documentation/uikit/app_and_environment/scenes). This is the default UI paradigm in iOS going forward, so Tangram should work correctly within it.
Why was it done differently before?
I think when this was implemented the first time, I misunderstood how touch events are handled in iOS view hierarchies. I probably thought that the gesture recognizers had to be on the front-most view to receive touch events, but in fact they'll receive any touch events that aren't handled by subviews (https://developer.apple.com/documentation/uikit/touches_presses_and_gestures/using_responders_and_the_responder_chain_to_handle_events).