One file recompiling on every build

In my Xcode project there is one file which always recompiles no开发者_JAVA技巧 matter what other file I change. I have tried to look for cycles of included headers and failed.

Is there a way to find out exactly what Xcode is trying to do?

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Open the Build Results window (Build -> Build Results / Shift+Cmd+B) before building.

Xcode may be recompiling the Prefix Header each time you make a change. In the build target settings, you can tell it to precompile the Prefix Header.