Greetings!
I'm preparing to publish an app in Apple Store.
It's a 2D Audio app made in Godot,
already published in Google Store..
As we know, OpenGL is considered deprecated since iOS 12 / 2018 ..
However given the current state of Metal, or Vulkan integration in Godot,
and with the idea of bringing the Best possible experience on iOS..
I'm not completely sure what will be the best API to use as primary option..
-As good as Metal, or even Vulkan work in Godot;
the fact of the matter is, each API has its strong and weak points..
-Metal:
Native on iOS, fully compliant and supported.
However it has two weak points:
Initial Compilation Freeze - +5 sec.
Performance Hit, (although negligible for final user)
app uses 25% more CPU (on my iPhone 12). Battery drain?
-Vulkan:
In godot, Vulkan > MoltenVk > Metal
More complex translation layer,
but interestingly gives slightly better Performance than Metal..
Initial Compilation doesn't cause Freeze,
because is lazy/delayed and performed while the app is starting.
Uses 25% less CPU than Metal and gives slightly more stable Framerate. (iPhone 12)
However, given the extra complexity it could be more prone to error, or Compatibility Problems,
which are known and have been reported with older iOS devices (iPads come to mind..)
Right?
-OpenGL:
No Initial Compilation Needed
Max Performance, No CPU munch
Universally supported, (in theory?)
works Perfectly on my iPhone 12 with iOS 26.3 and 26.4.2
And all in all, gives the best Performance and user experience.
-And that's pretty much the situation!
Since the graphics API of choice, will have an effect and directly translate to User experience...
what's then the best one?
-This will be the first app I Publish on Apple Store,
so as you can imagine I want to Comply with Apple as much as possible;
and bring iOS users the best possible experience.
However each one of the APIs seem to have a negative aspect..
Metal: 5sec Compilation Freeze
Vulkan: Compatibility Problems?
OpenGL: "Deprecated"
In practical terms, right now,
OpenGL gives the best Performance, and the best User Experience..
So what to do?
-The Android version is published in Google Store in OpenGL Compat mode.
Works perfectly.
Even tho OpenGL has been Deprecated on iOS for 7+ years,
it has survived all along, with no announced removal date from Apple.
And it seems to work perfectly and be fully operational up to the latest iOS 26 version.. right?
Maybe Apple is maintaining it for stability and compatibility reasons,
even if they're no longer actively developing it?
Butthee "deprecated" label sounds alarming,
as if support could drop any day..
So what will be the best choice in this situation?
-Will an app built primarily for OpenGL, (with Metal fallback)
be Rejected right away in Apple Store?
-Otoh Vulkan (via MoltenVK) could be a middle term solution,
second best Performance, no Compilation Freeze..
But yeah, the Compatibility aspect is important;
and while considerable improvements have been made in Godot's implementation,
the current status or possible outcome is harder to assess..
Both Metal and OpenGL seem safer options in that sense..
