Technical Q&A QA1788

Building a Position Independent Executable

Q: I received a "Non-PIE Binary - The executable '<appname>.app' is not a Position Independent Executable. Please ensure that your build settings are configured to create PIE executables." warning after uploading my app to iTunes Connect. How do I build my app as Position Independent Executable (PIE)?

A: Position Independent Executable (PIE) applications can be loaded at a random memory address when run. This has security benefits for your application. iOS 4.3 or later, and OS X 10.7 or later, fully support PIE executables.

Steps for building your application as PIE

In Xcode, select your target in the "Targets" section, then click the "Build Settings" tab to view its settings.
For iOS apps, set iOS Deployment Target to iOS 4.3 or later. For Mac apps, set OS X Deployment Target to OS X 10.7 or later.
Verify that Generate Position-Dependent Code is set at its default value of NO.
Verify that Don't Create Position Independent Executables is set at its default value of NO.

Verifying that your application was built as PIE

You can check whether your application is PIE by running otool -hv on your executable in the Terminal. Your application is PIE if its header contains the PIE flag. Listing 1 shows an example of how to do this for an iOS app.

Listing 1 Example of a PIE application

 $ otool -hv /path/to/MyApp.app/MyApp

MyApp:

Mach header

magic   cputype cpusubtype caps filetype  ncmds  sizeofcmds   flags

MH_MAGIC  ARM    V7        0x00  EXECUTE    23        2372     NOUNDEFS DYLDLINK TWOLEVEL PIE

Document Revision History

Date	Notes
2014-02-20	Clarified the notion of PIE for apps with dependencies.
2013-05-23	New document that addresses how to build a Position Independent Executable.