> Actually, most iOS games in recent years have been using Metal, as are most “off the shelf” engines internally.

Largely due to support in Unity/Unreal. They would be using OpenGL ES still if they had their own engines except maybe the biggest game studios that always have custom game engines/rendering integration.

iOS is not the largest mobile OS, so 100% of iOS could be doing something and it still wouldn't be "most of mobile" ;)

Most mobile users who matter (revenue).

Revenue per graphics API would be fascinating, albeit very different, investigation. It would likely also put OpenGL on desktop in a very different light given the professional products still using it.

iOS is definitely the most used mobile OS.

Do you have a link for that stat? Last time I looked android was quite a way in front in global market share[1] . Happy to be proven wrong.

[1]: https://www.idc.com/promo/smartphone-market-share/os

I don't consider "Android" to be an OS. It is like Linux, there are a hundred different OSes all running on top of the same kernel and framework. For example, the OS Samsung runs on their phones is so different from the OS Xiaomi runs on theirs that a casual user might think it's a completely different system.

So lumping together all of these variants and calling them "most used OS" is not useful in any sense. They are very different for users, and very different for devs.

This is specially relevant when you want to develop a game against a graphics API. Samsung has Vulkan on their flagships for a couple years now, but not the mid/low-end devices. Pixel supports Vulkan, but the units sold are so low that they are a rounding error. No other major manufacturer significantly supports Vulkan either. In this and similar scenarios, the framework used by ios may well be the "most used" mobile framework.

> I don't consider "Android" to be an OS.

Then you're correct by your definition, but not by most people's definition.