Secret Keys

Often keys are required for configuring analytics or accessing services for an iOS app and these keys are sometimes hard-coded or added to the app's Info.plist. Placing these strings into source control, especially for Open Source projects, exposes these protected configuration values to more people than you may like.

How It Works

For this sample project a file is placed at ~/.secretkeys which is simply a shell script which exports some variables.

export Greeting="Hello!"
export SecretCode="1234"
export SecretToken="abc123"

In the app a file named Keys.plist has default values which are replaced when the build is run.

<plist version="1.0">
<dict>
        <key>Greeting</key>
        <string>DEFAULT</string>
        <key>SecretCode</key>
        <string>DEFAULT</string>
        <key>SecretToken</key>
        <string>DEFAULT</string>
</dict>
</plist>

The script named update_keys.sh in the root of the project directory is run by a build script called Update Keys in Build Phases which is placed after Copy Bundle Resources so it modifies Keys.plist after it is copied to the build output folder.

Placing update_keys.sh at the root of the project directory instead of the Build Phases makes it easier to edit as there may be changes needed from time to time and editing within the Xcode Build Phases is not ideal for editing shell scripts.

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Brennan Stehling - 2015