iOS - how to create constants in private and public scope

iOS - constants declaration.m

// ----------------------------------
//declaration in PRIVATE scope (for using only in your class)
// ----------------------------------
// declare in .m
static const int kTweetMaxCharacters = 140;
static NSString * const kHelloString = @"HELLO!";

// ----------------------------------
// declaration in PUBLIC scope (for using in other classes too)
// ----------------------------------
// declare in .h
extern const int FGTweetMaxCharacters;
extern NSString * const FGTweetSentNotificationName;

// declare in .m   *** Notice there is NO `static`. ***
const int FGTweetMaxCharacters = 140;
NSString * const FGTweetSentNotificationName = @"FGTweetSentNotificationName";

This was handy--first thing I saw on Google to list the syntax for declaring NSTimeInterval constants. Props.