How does cocos utilize OpenGL on ios?

cocos2d-x Obj-C
1

the article here mentioned 2 approaches:
multiple context with a single shared group and single contex with multiple destination framebuffers. which one is used?

https://developer.apple.com/library/archive/documentation/3DDrawing/Conceptual/OpenGLES_ProgrammingGuide/WorkingwithOpenGLESContexts/WorkingwithOpenGLESContexts.html#//apple_ref/doc/uid/TP40008793-CH2-SW5

given that ## OpenGL ES Restricts Each Context to a Single Thread