Pre-Packaging Scripts

8.4. What's a "Pre-Packaging Script" and Why Would I Need One?

A pre-packaging script is a custom script that the Darwin Build Environment can execute before the final packaging (e.g., creating the .ipa or .app bundle) of your application but after the compilation and linking stages.

Purpose and Use Cases:

You might need a pre-packaging script for tasks such as:

1. Modifying Plist Files:

   • Programmatically changing values in your app's Info.plist file (e.g., updating build numbers, version strings, or custom keys based on build configurations).

2. Copying or Modifying Resources:

   • Copying specific resource files into the app bundle that aren't handled by the standard build process.

   • Processing or transforming resource files (e.g., optimizing images, processing data files).

3. Running Custom Tools:

   • Executing other command-line tools or scripts that need to operate on the compiled application bundle before it's signed and packaged.

4. Conditional Logic:

   • Implementing conditional logic that alters the app bundle based on build flags or environment variables.

How to Use a Pre-Packaging Script:

1. Create Your Script:

   • Write a script that performs the desired actions. This can be a Windows batch script (.cmd or .bat), a PowerShell script (.ps1), or any executable program.

   • The script will typically operate on the files within the staging area where the app bundle is being assembled (often a build or Payload directory). The exact path and structure might need to be determined by inspecting the build process or environment variables available to the script.

2. Specify the Script in make.cmd:

   • Open your project's make.cmd file.

   • Define or modify the DBE_PREPACK_SCRIPT variable to point to your custom script:

     set DBE_PREPACK_SCRIPT=path\to\your\custom_script.cmd

     Replace path\to\your\custom_script.cmd with the actual path to your script. You can use relative paths from the project root or absolute paths.

3. Ensure Script is Executable:

   • Make sure the script has the necessary execute permissions and that any interpreters it requires (like PowerShell) are available in the system's PATH.

When you build your project, if DBE_PREPACK_SCRIPT is defined, the build system will execute this script at the appropriate stage. Any output from your script will typically appear in the build log.

Example Scenario: Imagine you want to inject the current Git commit hash into your Info.plist. Your custom_script.cmd might look something like this (simplified):

@echo off
REM Assuming Info.plist is in a known relative location, e.g., Payload/YourApp.app/Info.plist
set PLIST_PATH=Payload\YourApp.app\Info.plist

REM Get Git commit hash (requires Git in PATH)
for /f %%i in ('git rev-parse --short HEAD') do set GIT_HASH=%%i

echo Updating Info.plist with Git hash: %GIT_HASH%

REM Use a command-line plist utility (like plutil or similar if available, or a custom tool)
REM to set a key, e.g., CFBundleVersionShortString, to %GIT_HASH% in %PLIST_PATH%
REM For example (this is pseudo-code for the plist update part):
REM some_plist_tool.exe -set CFBundleGitVersion %GIT_HASH% %PLIST_PATH%

echo Pre-packaging script finished.