Xcode 4 can't locate public header files from static library dependency

Alternate titles to aid search

• Xcode can't find header
• Missing .h in Xcode
• Xcode .h file not found
• lexical or preprocessor issue file not found

I'm working on an iOS application project which came from Xcode 3. I have now moved to Xcode 4 my project builds a number of static libraries.

Those static libraries also declare public headers and those headers are used by the application code. In Xcode 3.x the headers were copied (as a build phase) to the public headers directory, then in the application project the public headers directory was added to the headers search list.

Under Xcode 4 the build directory is moved to ~/Library/Developer/Xcode/DerivedData/my-project.

The problem is how do I reference this new location in the headers search settings? It seems that:

• public headers directory is relative to DerivedData directory, but
• headers search directory is relative to something else (possibly the project location)

How should I set up a static library target for iOS development in Xcode 4 that will ensure the header files are made available to the clients that use the static library when trying to compile as a dependancy?