End-to-end on iOS sim: UIKitPlatform boots an SxAppDelegate, installs
an SxGLView (UIView subclass overriding +layerClass to return
CAEAGLLayer) as the root view controller's view, sets the drawable
properties (EAGLColorFormatRGBA8, non-retained backing — looked up by
dlsym so pointer-identity-checked constants match), creates an
EAGLContext (GLES3), and registers a CADisplayLink that invokes the
user's frame closure on every vsync. end_frame presents the
renderbuffer via [EAGLContext presentRenderbuffer:].
The renderbuffer is allocated lazily in -[SxGLView layoutSubviews] once
the layer has its real on-screen bounds — allocating earlier (e.g. in
didFinishLaunching) failed with INCOMPLETE_ATTACHMENT because the
SxGLView's frame was still zero at that point. Setting the SxGLView
as the VC's `view` (via setView:) lets the standard VC layout pipeline
size it to the window without us having to read CGRect struct returns
from objc_msgSend.
EAGL drawableProperties dict keys/values are dlsym'd from OpenGLES —
the framework checks them by pointer identity, so synthesized NSString
literals with the same contents don't work.
examples/66-uikit-platform.sx — runnable smoke test that cycles the
screen color (red → green → blue every 30 frames) so you can confirm
the display-link tick and present pipeline.
modules/opengl.sx gains glGenFramebuffers, glGenRenderbuffers,
glBindFramebuffer, glBindRenderbuffer, glFramebufferRenderbuffer,
glGetRenderbufferParameteriv, glCheckFramebufferStatus — needed for
the iOS GLES FBO-to-renderbuffer setup. They're wired into load_gl
so SDL and the iOS dlsym loader both pick them up.
Compiles cleanly on macOS / WASM / iOS-sim. Non-iOS targets never
reference the unresolved UIKit/QuartzCore/OpenGLES symbols because
every Obj-C touch lives inside `inline if OS == .ios`.
Game's iOS path still goes through SDL3 for now. Touch events + game
wire-up + keyboard observer = next steps.
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