iphoneobjective-cdead-code

Are unused classes compiled by Xcode when building an app?

If something is not used in C++, it's not compiled at all. Is the same true for iPhone? If I compile a program and there are unused classes or other stuff, will it be compiled or ignored?

Solution

  • It depends on your build settings.

    Under your target build settings, then under "Linking" there is an option for "Dead Code Stripping". It defaults to yes for projects created with Xcode.

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    Here's a link to the build settings documentation from Apple (with an excerpt):

    https://developer.apple.com/library/archive/documentation/DeveloperTools/Reference/XcodeBuildSettingRef/1-Build_Setting_Reference/build_setting_ref.html

    DEAD_CODE_STRIPPING (Dead Code Stripping)

    Description: Boolean value.

    Specifies whether dead code is stripped from the binary.

    Prerequisite: $GCC_DEBUGGING_SYMBOLS = full

    Values:

    YES: Dead code is stripped from the binary when the prerequisite is met.

    NO: Dead code is not stripped from the binary.

    Default value: NO Companions: “GCC_DEBUGGING_SYMBOLS (Level of Debug Symbols).” Prerequisite for: PRESERVE_DEAD_CODE_INITS_AND_TERMS

    Note, the docs say the value defaults to NO, but Xcode project settings default the value to YES.