I've added something in -prefix.pch file, but XCode gives me error when I use it, saying

> 
> Use of undefined identifier ...
> 
> 
> 

However if I compile it (Command+B), it compiles, so I thought it was caused by derived data, I then tried to remove derived data (thus to force it to be re-generated again) but in Organizer there was NO derived data for the project, I also tried Clean but does not work.

Can anyone help?

edit: the macro I defined is not important for the question, but here is the macro:

```
#define IPAD (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)

```

edit 2: I added Kiwi as unit test tool to the project, probably something in project settings are changed which caused the problem.