Export to macOS and iOS

Mac libraries that are intended to be shared with other people require Code Signing and Notarization. For this you will need:

A Mac Computer
An Apple ID enrolled in Apple Developer Program (99 USD per year)

Without Code Signing and Notarization, the other person can still use the built library, but either needs to:

rebuild the whole thing locally
re-sign it
accept that it may contain malicious code.

Prerequisites:

Download and install Xcode on your Mac computer.

Building macOS universal lib

Add both x64 and arm64 targets. This is needed in order to create a universal build.

rustup target add x86_64-apple-darwin
rustup target add aarch64-apple-darwin

Build the library for both target architectures:

cargo build --target=x86_64-apple-darwin --release
cargo build --target=aarch64-apple-darwin --release

Run the lipo tool to merge the two in one universal library.

lipo -create -output target/release/lib{YourCrate}.macos.dylib \
    target/aarch64-apple-darwin/release/lib{YourCrate}.dylib \
    target/x86_64-apple-darwin/release/lib{YourCrate}.dylib

The result of this will be the file target/release/lib{YourCrate}.macos.dylib that will now have support for both x64 and arm64 platforms.

The user would need to replace {YourCrate} with the crate name. The name of your library will be the one you provided in Cargo.toml file, prefixed with lib and followed by .dylib:

[package]
name = "{YourCrate}"

Next, you will need to create the .framework folder.

mkdir target/release/lib{YourCrate}.macos.framework
cp target/release/lib{YourCrate}.macos.dylib \
    target/release/lib{YourCrate}.macos.framework/lib{YourCrate}.macos.dylib

Next, create the Info.plist file inside the Resources folder:

mkdir target/release/lib{YourCrate}.macos.framework/Resources

File contents:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>CFBundleExecutable</key>
    <string>lib{YourCrate}.macos.dylib</string>
    <key>CFBundleIdentifier</key>
    <string>org.mywebsite.myapp</string>
    <key>CFBundleInfoDictionaryVersion</key>
    <string>6.0</string>
    <key>CFBundleName</key>
    <string>My App Name</string>
    <key>CFBundlePackageType</key>
    <string>FMWK</string>
    <key>CFBundleShortVersionString</key>
    <string>1.0.0</string>
    <key>CFBundleSupportedPlatforms</key>
    <array>
        <string>MacOSX</string>
    </array>
    <key>NSHumanReadableCopyright</key>
    <string>Copyright (c)...</string>
    <key>CFBundleVersion</key>
    <string>1.0.0</string>
    <key>LSMinimumSystemVersion</key>
    <string>10.12</string>
</dict>
</plist>

XML format

The CFBundleExecutable name must match the dylib file name. Some of the contents in the XML file must not contain some characters. Generally avoid using anything other than letters and numbers. Related StackOverflow issue.

Edit the project's .gdextension file to include support for macOS. This file will probably be at godot/{YourCrate}.gdextension. The format will be similar to the following:

[libraries]
...
macos.release = "res://../rust/target/release/lib{YourCrate}.macos.framework"

Building an iOS library

Add as target arm64 iOS.

rustup target add aarch64-apple-ios

Build the library:

cargo build --target=aarch64-apple-ios --release

The result of this will be the file target/aarch64-apple-ios/release/lib{YourCrate}.dylib.

Next, you will need to create the .framework folder.

mkdir target/release/lib{YourCrate}.ios.framework
cp target/release/lib{YourCrate}.ios.dylib \
    target/release/lib{YourCrate}.ios.framework/lib{YourCrate}.ios.dylib

Next, create the Info.plist file inside the .framework folder, with the following contents:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>CFBundleInfoDictionaryVersion</key>
    <string>6.0</string>
    <key>CFBundleDevelopmentRegion</key>
    <string>en</string>
    <key>CFBundleExecutable</key>
    <string>lib{YourCrate}.ios.dylib</string>
    <key>CFBundleName</key>
    <string>My App Name</string>
    <key>CFBundleDisplayName</key>
    <string>My App Name</string>
    <key>CFBundleIdentifier</key>
    <string>org.my-website.my-app</string>
    <key>NSHumanReadableCopyright</key>
    <string>Copyright (c) ...</string>
    <key>CFBundleVersion</key>
    <string>0.12.0</string>
    <key>CFBundleShortVersionString</key>
    <string>0.12.0</string>
    <key>CFBundlePackageType</key>
    <string>FMWK</string>
    <key>CSResourcesFileMapped</key>
    <true/>
    <key>DTPlatformName</key>
    <string>iphoneos</string>
    <key>MinimumOSVersion</key>
    <string>12.0</string>
</dict>
</plist>

See XML format requirements above.

Edit the project's .gdextension file to include support for iOS. This file will probably be at godot/{YourCrate}.gdextension. The format will be similar to the following:

[libraries]
...
ios.release = "res://../rust/target/release/lib{YourCrate}.ios.framework"

Code Signing and Notarizing (macOS only)

Optional Step

This step is only needed if you want to share the library. If you are building the whole game, you will sign everything and don't need to sign the library. You can skip to Godot Build step.

In order to code-sign and notarize your app, you will first need to gather some information from your enrolled Apple Developer account. We will create corresponding environment variables and use a script to sign, so it's easier to run. Here are the environment variables needed:

APPLE_CERT_BASE64
APPLE_CERT_PASSWORD
APPLE_DEV_ID
APPLE_DEV_TEAM_ID
APPLE_DEV_PASSWORD
APPLE_DEV_APP_ID

Firstly, make sure to enroll your Apple ID to the Developer Program:

Create an Apple ID if you don't have one already.
Use your Apple ID to register in the Apple Developer Program by going to developer.apple.com.
Accept all agreements from the Apple Developer Page.

`APPLE_DEV_ID` - Apple ID

Your email used for your Apple ID.

APPLE_DEV_ID = email@provider.com

`APPLE_DEV_TEAM_ID` - Apple Team ID

Go to developer.apple.com. Go to account.

Go to membership details. Copy Team ID.

APPLE_DEV_TEAM_ID = 1ABCD23EFG

`APPLE_DEV_PASSWORD` - Apple App-Specific Password

Create Apple App-Specific Password. Copy the password.

APPLE_DEV_PASSWORD = abcd-abcd-abcd-abcd

`APPLE_CERT_BASE64`, `APPLE_CERT_PASSWORD` and `APPLE_DEV_APP_ID`

Go to developer.apple.com. Go to account.

Go to certificates.

Click on + at Certificates tab. Create Developer ID Application. Click Continue.

Leave profile type as is. Create a certificate signing request from a Mac. You can use your own name and email address. Save the file to disk. You will get a file called CertificateSigningRequest.certSigningRequest. Upload it to the Developer ID Application request. Click Continue.

Download the certificate. You will get a file developerID_application.cer.

On a Mac, right click and select open. Add it to the login keychain. In the Keychain Access app that opened, log into Keychain tab, go to Keys, sort by date modified, and expand your key (the key should have the name you entered at Common Name). Right click the expanded certificate, get info, and copy the text at Details -> Subject Name -> Common Name. For example:

APPLE_DEV_APP_ID = Developer ID Application: Common Name (1ABCD23EFG)

Then, select the certificate, right click and click export. At file format select p12. When exporting, set a password for the certificate. This will be the value of APPLE_CERT_PASSWORD. You will get a Certificates.p12 file.

For example:

APPLE_CERT_PASSWORD = <password_set_when_exporting_p12>

Then you need to make a base64 file out of it, by running:

base64 -i Certificates.p12 -o Certificates.base64

Copy the contents of the generated file, e.g.:

APPLE_CERT_BASE64 = ...(A long text file)

After these secrets are obtained, all that remains is to set them as environment variables. Afterwards you can use the following script for signing ci-sign-macos.ps1. In order to run this script you will need to install powershell on your Mac.

ci-sign-macos.ps1 target/release/{YourCrate}.framework

External script disclaimer

The user is responsible for the security and up-to-dateness of the script.

Godot Build

After building the libraries, you can now distribute them as they are, or build the whole game using Godot. For that, follow Godot's How to export guide:

The godot-rust Book