Go SDL2 Portable macOS Binary

A simple application that shows how to build an SDL2 mac app with the Go Language.
This assumes you have followed all setup available from https://github.com/veandco/go-sdl2

License

Please be aware while this project is licensed under the MIT license, the projects for SDL2 and go-sdl2 have other licenses, while I waive the right to keep the copy of this project's MIT license with the shareable executable project, you still have to include and abide by the other projects requirements when sharing.
As such:

• SDL2 binding for Go retains its BSD-3-Clause license,
• SDL2 retains the Z-lib license
• While the Go files provided in this template repository and this readme are licensed under the MIT

Steps to build on macOS

Building SDL2 for universal builds

1. Build SDL2 from source
   1. a. SDL2 is available from “ https://github.com/libsdl-org/SDL * “ you will need cmake and make to build it, open the terminal in the downloaded SDL2 folder, and run the following to build the universal library.

mkdir build && cd build
cmake .. -DCMAKE_OSX_ARCHITECTURES="arm64;x86_64"
make
otool -L libSDL2-2.0.0.dylib

The above may take a while but when it is done you should get an output telling you what native libraries libSDL2-2.0.0.dylib is linking against (this file should also be fully portable.)

* make sure you are using SDL2 and not SDL3, you will have to swap to the correct branch to make sure you are using the right one

2. Copy the newly built dylib (libSDL2-2.0.0.dylib) to usr/local/lib as the Go build system will need this file (keep a copy available as you will need it later.)

Building your SDL App for both x86-64 and arm64

Now once you have written your code you can do the following to build and link your files, this won't go into building an app bundle as is the standard way to share mac binaries.

This guide uses the names like awesomeOutputARM64, and awesomeOutputAMD64, you can change these names to whatever works for you or rename your files at the end so you can just copy-paste the commands (I may create a script that automates these steps at a later date.)

AMD64 (x86-64) binary

For AMD64 in your Go project folder run the following command

GOARCH=amd64 GOOS=darwin CGO_ENABLED=1 go build -o awesomeOutputAMD64 .

This will output an AMD64 binary from your Go code

ARM64 binary

For regular ARM64 binaries, you can either rely on the regular go build command, or use the below to keep the process simple

GOARCH=arm64 GOOS=darwin CGO_ENABLED=1 go build -o awesomeOutputARM64 .

Now with the two separate binaries, if the builds succeeded, you can run the following commands to confirm that they are built for AMD64 and ARM64 respectively.

lipo -info awesomeOutputAMD64
lipo -info awesomeOutputARM64

you should see an output of

Non-fat file: awesomeOutputAMD64 is architecture: x86_64
Non-fat file: awesomeOutputARM64 is architecture: arm64

If all has worked you can move onto the next steps

Building the Universal Go Binary

At this point with the two executables you can run the following command to create a fat/universal binary

lipo -create -output ./awesomeOutputUniversal ./awesomeOutputARM64 ./awesomeOutputAMD64 
lipo -info awesomeOutputUniversal

you should get the following output, as well as a new binary alongside the two separate architecture binaries

Architectures in the fat file: awesomeOutputUniversal are: x86_64 arm64

Making it Portable

Now to make it portable (this is not an app bundle, but the same logic can be used, just alter commands as needed, where needed.) First run the following command in your terminal

otool -L awesomeOutputUniversal

This should output something like the following (if you are using other SDL2 libraries, or just other libraries in general, you can modify the commands I have provided to create a portable library, and the output below will differ.)

awesomeOutputUniversal (architecture x86_64)
    @rpath/libSDL2-2.0.0.dylib (compatibility version 3101.0.0, current version 3101.0.0)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1351.0.0)
    /usr/lib/libresolv.9.dylib (compatibility version 1.0.0, current version 1.0.0)
awesomeOutputUniversal (architecture arm64)
    @rpath/libSDL2-2.0.0.dylib (compatibility version 3101.0.0, current version 3101.0.0)
    /System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation (compatibility version 150.0.0, current version 3107.0.0)
    /usr/lib/libresolv.9.dylib (compatibility version 1.0.0, current version 1.0.0)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1351.0.0)

To make your application portable you are only interested in the lines that say things like @rpath, or have your username in them. For SDL2 in this application the line is @rpath/libSDL2-2.0.0.dylib

You can then run the following command to finally make your universal application portable

install_name_tool -change "@rpath/libSDL2-2.0.0.dylib" "@executable_path/./libSDL2-2.0.0.dylib" awesomeOutputUniversal

Now you can share your Go application that uses SDL2 with other macOS users

Notes on app bundles

To make an app bundle portable, most of the above does apply with minor alterations, the most important of which is the last command, which will change to

install_name_tool -change "@rpath/libSDL2-2.0.0.dylib" "@executable_path/../Frameworks/libSDL2-2.0.0.dylib" awesomeOutputUniversal

Since your typical macOS app bundle will have the following structure

-awesomeApp.app
    -info.plist
    -Frameworks
        -libSDL2-2.0.0.dylib
    -MacOS
        -awesomeAppUniversal
    -Resources
        -awesomeAppIcon.icns
        -other app resources like images

Typically a mac app bundle would have the same name for the file in the MacOS folder and the app bundle, but just to avoid confusion with the commands I have named them differently.