Defining constants on header file

Is there any way to automate the following process?

So I create a private constant in the .m file, making it private:

static CGFloat const kHeight = 30.0f;

And then I decide I need it to be public. Can I automate the addition of:

FOUNDATION_EXPORT CGFloat *const kHeight;

or 

extern CGFloat const kHeight;

to the header file? Even if it's not there by default, can I add this myself somehow?

Thanks.