M1 support

[Kylmakalle]

While tdlib can be built for arm64 devices, it still lacks support of arm64 simulators and macOS targets. That means we're required to use EXCLUDED_ARCHS = arm64 in XCode development and even use Apple Rosetta on M1 macs which makes some people struggle (#1555, tdlight-team/tdlight-java#28) building tdlib.

This PR introduces arm64 support for macOS & simulator targets

• Patch OpenSSL with separate simulators target (cause lipo can't merge multiple platforms with same arch).
  Results in DOUBLED time to build openSSL for non macOS platforms 😞
• Patch OpenSSL with macOS arm64 target without any asm optimizations.
  Any optimizations possible only for OpenSSL 1.1.1 which is another TODO
• Added arm64 in tdlib iOS.cmake destinations for simulators
• Added arm64 option in build.sh for cmake macOS targets
• Change build scripts to provide separate binaries and linking for devices and simulators separately
• Combine result dylib's to .xcframework
• @levlam Describe -DCMAKE_OSX_ARCHITECTURES="x86_64;arm64" for macOS build in main readme.md
• (Optional) Provide test project that will cover initial framework implementation

[levlam]

CMake has basic framework generation support: https://cmake.org/cmake/help/v3.5/prop_tgt/FRAMEWORK.html#prop_tgt:FRAMEWORK.

But I'm not sure, whether it could be useful for multi-arch builds.

[Kylmakalle]

CMake has basic framework generation support:
But I'm not sure, whether it could be useful for multi-arch builds.

That's not our option for tdlib unfortunately, we still unable to link and pack it in one framework. Here's note in CMake Gitlab thread which suggests to move on xcframeworks as well.

[Kylmakalle]

I assume that I've reached this PR goal.
Now we're just replacing bare dylibs with xcframeworks that includes arm64 to be able to run tdlib on M1 nativelly.
🛠 Full build example on Github Actions

This PR does not optimize arm code, library packaging, linking, headers and so on.
I would rather make another PR for Readme.md and link my standalone repo that provides pre-build binary in modern Swift Package and App example to quickly jump into development.

[levlam]

Currently, with this patch applied we have problems with ordinary build on macOS without the example usage, because brew-installed OpenSSL supports only one architecture.

[levlam]

Probably, CMAKE_OSX_ARCHITECTURES shouldn't be changed in the main CMakeLists.txt, only passed in build.sh as another argument to cmake on "macOS" platform.

[Kylmakalle]

Moved -DCMAKE_OSX_ARCHITECTURES="x86_64;arm64" as custom flag for build.sh
🛠 Github Actions Build

@levlam Upon accepting this MR, add docs to main readme please.
Cause binary will not be build for arm64 by default on Intel (x86_64) CPUs.
You can phrase it as you like or even use GitHub "edit as maintainer" thing.

[Kylmakalle]

P.S. I've faced same issue in short investigation with brew-installed openssl. Will dive a bit more deeply.

[Kylmakalle]

Universal pre-built OpenSSL binary installation can be achieved with MacPorts

sudo port install openssl
...
--->  Attempting to fetch openssl-1.1.1k_0.darwin_20.x86_64.tbz2 from https://packages.macports.org/openssl

file /opt/local/bin/openssl   
/opt/local/bin/openssl: Mach-O 64-bit executable x86_64

using +universal flag which brew lacks of due to removal in 2017 (current build script)

sudo port install openssl
...
--->  Attempting to fetch openssl-1.1.1k_0+universal.darwin_20.arm64-x86_64.tbz2 from https://packages.macports.org/openssl

file /opt/local/bin/openssl   
/opt/local/bin/openssl: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit executable x86_64] [arm64:Mach-O 64-bit executable arm64]
/opt/local/bin/openssl (for architecture x86_64):	Mach-O 64-bit executable x86_64
/opt/local/bin/openssl (for architecture arm64):	Mach-O 64-bit executable arm64

Make sure to install OpenSSL version >= 1.1.1i cause it officially supports arm64

P.S. I also prefer brew more but this missing flag sucks :)

[levlam]

Thanks @Kylmakalle for these awesome changes! Sorry that merging this took so long.

[sapoepsilon]

@levlam Would you mind adding this page and changing this to Swiftgram in README, since this wrapper is not updated anymore. It could have saved me about 2 hours if I knew it was there. I had to manually find it through issues. Thank you!

@Kylmakalle Thanks for the update! I was able to build the TDLib with your instructions on M1. Is there any difference between using your wrapper for M1 and using the TDLib?

[Kylmakalle]

@sapoepsilon TDLibKit is a Swift wrapper with pre-generated classes, types and a little "sugar". TDLibFramework is just a pre-built fat xcframework binary. Both now based on recent TDLib commits with M1 support as well. More info in each project READMEs.

[levlam]

@sapoepsilon This is a merged pull request, so all changes are present in the master branch. Swiftgram/TDLibKit has just been added to the list of examples as you suggested.