Tracing variable-usage within a whole project (objc)

Hi,

I have the need of tracing all uses of a variable within all source-files of an objective-c-project.
As I can see, there are already classes for handling dataflow-things, but for the moment i have
no clue what classes would be appropriate to help me with my problem.
Are there already classes within clang which are solving it and when not, which of them can help
me?

Greetings,
Hendrik