Add ios support

[Markos-Th09]

Add support for iOS. and the ASTC texture format.

[IsaacMarovitz]

As far as I can tell the ASTC changes have nothing to do with iOS support and should be moved to another PR.

[Markos-Th09]

@DarioSamo @IsaacMarovitz other than that is there anything else to discuss?

[IsaacMarovitz]

Do you have a way to run the example projects on iOS?

[Markos-Th09]

Do you have a way to run the example projects on iOS?

Yes, although I did not include it here. I have been also developing a port of Unleashed Recompiled for iOS (hopefully coming soon) and so far these changes have been enough.

[IsaacMarovitz]

There seems to be some problems with signing that prevent file_to_c and spirv_cross_msl from working.

[Markos-Th09]

There seems to be some problems with signing that prevent file_to_c and spirv_cross_msl from working.

I didn't use the Xcode generator for building for iOS if you used that. With the make or ninja generators I did not encounter any issues.

Getting it on device is a bit more convoluted this way so I will investigate what is happening with the Xcode generator.

Edit: I made it work with the Xcode generator you can try again.

[IsaacMarovitz]

Can you share the command you used?

cmake -B cmake-ios -G Xcode -DCMAKE_TOOLCHAIN_FILE=./contrib/ios-cmake/ios.toolchain.cmake -DPLATFORM=OS64 -DPLUME_BUILD_EXAMPLES=ON

This worked on my machine as far as cmake is concerned, but it tried to compile using macOS system SDL2 which doesn't contain the binaries or headers for iOS.

[Markos-Th09]

Can you share the command you used?

cmake -B cmake-ios -G Xcode -DCMAKE_TOOLCHAIN_FILE=./contrib/ios-cmake/ios.toolchain.cmake -DPLATFORM=OS64 -DPLUME_BUILD_EXAMPLES=ON

This worked on my machine as far as cmake is concerned, but it tried to compile using macOS system SDL2 which doesn't contain the binaries or headers for iOS.

Sure. I actually used vcpkg to get a build of SDL2 for iOS, so my configure command was:
cmake -B build/ios -DPLUME_BUILD_EXAMPLES=ON -G Xcode -DCMAKE_TOOLCHAIN_FILE=vcpkg/scripts/buildsystems/vcpkg.cmake -DVCPKG_CHAINLOAD_TOOLCHAIN_FILE=contrib/ios-cmake/ios.toolchain.cmake -DPLATFORM=OS64

Either clone vcpkg in the same directory and bootstrap it or if you already have it set up just proceed with installing SDL2. The target triple for ios is arm64-ios, so you can use vcpkg install sdl2:arm64-ios or use a proper vcpkg.json.

Should I add vcpkg to this PR?

[Markos-Th09]

@IsaacMarovitz were you able to build it this way?

[Markos-Th09]

@IsaacMarovitz I just wanted to following up on this. Were you able to get the iOS examples building using the vcpkg and the commands shared above?

[Markos-Th09]

@IsaacMarovitz @DarioSamo
Regarding recent changes the current semantics of PLUME_MACOS and PLUME_IOS is rather incorrect based on the context they are used. Including catalyst from PLUME_MACOS is incorrect PLUME_MACOS as catalyst expects the usage of iOS style APIs and macOS APIs are unavailable so this would lead to non functional code. In general the code currently written for iOS covers the broad TARGET_OS_IPHONE category which includes are non-macOS platforms (iOS, iPadOS, watchOS, tvOS). The iOS style code should also be used when TARGET_OS_SIMULATOR is defined. In general it is better to gate things based on the corrected PLUME_MACOS.

/// macOS
#ifndef PLUME_MACOS
#    define PLUME_MACOS               TARGET_OS_OSX
#endif

If the goal of PLUME_MACOS is to indicate whether it is running on a Mac, it should not be used to decide whether macOS APIs are to be used.

As TargetConditionals.h states:

 *    TARGET_OS_MAC                - Generated code will run on a variant of macOS
 *      TARGET_OS_OSX                - Generated code will run on macOS
 *      TARGET_OS_IPHONE             - Generated code will run on a variant of iOS (firmware, devices, simulator)
 *        TARGET_OS_IOS                - Generated code will run on iOS
 *          TARGET_OS_MACCATALYST        - Generated code will run on macOS
 *        TARGET_OS_TV                 - Generated code will run on tvOS
 *        TARGET_OS_WATCH              - Generated code will run on watchOS
 *        TARGET_OS_VISION             - Generated code will run on visionOS
 *        TARGET_OS_BRIDGE             - Generated code will run on bridge devices
 *      TARGET_OS_SIMULATOR          - Generated code will run on an iOS, tvOS, watchOS, or visionOS simulator
 *      TARGET_OS_DRIVERKIT          - Generated code will run on macOS, iOS, tvOS, watchOS, or visionOS

[IsaacMarovitz]

I think you can assume PLUME_MACOS is generally meant to mean TARGET_OS_OSX. I don't think we care or want to support TARGET_OS_MACCATALYST or TARGET_OS_SIMULATOR