iOS support

[adamski]

What might be required to get this library running on iOS?

[mtytel]

would probably just need a modified version of windowing_macos.mm and some better handling of touch events.

[danielraffel]

Hey Matt — I've been working on iOS support for Visage and wanted to check in before opening any upstream PRs.

I have a series of 7 small, stacked PRs on my fork that add iOS support including multi-touch. They're structured to be incremental. Each builds on the previous one and doesn't break existing platforms. Here's what they cover:

#	What	Size
1	CMake iOS platform detection	2 lines
2	Shared Apple code guards	~18 lines
3	iOS CMake source routing	~10 lines
4	iOS windowing implementation + tests (MTKView + Metal, Catch2)	~570 lines (all new files)
5	pointer_id API (int pointer_id = 0 on MouseEvent/Window)	~126 lines
6	Multi-pointer dispatch in WindowEventHandler	~300 lines
7	iOS multi-touch wiring + tests (6 Catch2 test cases)	~385 lines

All desktop platforms are unaffected. The multi-touch API uses default parameter values (pointer_id = 0) so every existing call site compiles unchanged.

I've been testing this with a JUCE audio plugin (griddy-v2) running Visage as the GPU UI on both macOS and iOS. Multi-touch works: dragging an XY pad with one finger while adjusting a slider with another, multiple sliders simultaneously, etc.

The PRs are merged to main on my fork so I can use them more easily. PR #11 has the full series overview in its description.

Would you be open to me opening these as upstream PRs? Happy to adjust the structure, ordering, or anything else. Just wanted to check before submitting.