The same code on any other device will yield the same results. The problem is your code, not iOS.
And I told you to use a real device for debugging purposes.
I told you to Capture an OpenGL ES Frame.
As in, run the project on a real device, go to Xcode, select Product->Debug->Capture OpenGL ES Frame.
Now you can single-step through every OpenGL ES call, or just the render calls, and see everything about the context and look for what could be wrong.
You should count your blessings that you are on iOS. There is no such feature on Android™.
If you can’t figure it out on your own after doing this, go to the draw call that you think should be drawing a quad and post a screenshot.