qtcreator in how to use cocoa api

Use qt development on mac machine, how to use cocoa api methods?
I add import works in the header file,
But the compiler, however, reported that more than N can not find @ + - symbols.

mac os: 10.6.x
xcode: 3.1
qt: 4.8.0

There is no relevant information online little ah.
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Try it changed to include
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Suffix gotta be. Mm can be compiled.
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Solve the scattered points ~ ~ ~ ~
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cocoa class defined in the Foundation framework in many