I am building an iOS static lib using Xcode4.4. But when i come to setting the visibility of headers, I can’t see any options. Normally there should be some options like Public, Private, Project. Having compared to some other lib projects, I still can’t find the problem…
The screenshot of file inspector when I chose Hellor.h looks like this:

Things did change since Xcode 4.4. I ask Apple Developer Technical Support for help, and here is reply:
In the latest Xcode, exported headers are setup under the Build Phases of your target library. By default, the static library template creates a “Copy Files” phase. Any headers added to this phase will be copied to the include directory for the library and hence “made public”. If your project lacks a “Copy Files” build phase, follow the instructions under “Configuring Exported Headers” in the “Creating the Library” section of the “Using Static Libraries in iOS” guide to create and configure the phase. https://developer.apple.com/library/ios/#technotes/iOSStaticLibraries/Articles/creating.html