Use of extern in Objective C

Question

How good is it to use extern in Objective C? It does make coding for some parts easy.. but doesn\'t it spoil the object orientation?

Answer 1

Depends on your need, for example you have login page. After you logged in you are notifying to other pages in the applications.

#import 

extern NSString *const DidLoginNotification;

@interface LoginViewController : NSObject
- (void)login;
@end


// LoginViewController.m
#import "LoginViewController.h"

//define extern const in implementation file only once for the whole process
NSString *const DidLoginNotification =
    @"DidLoginNotificationNotified";

@implementation LoginViewController

- (void)login {
    // Perform notification
    [[NSNotificationCenter defaultCenter];
    sendNotificationName: DidLoginNotification
                    object:nil];
}

The notification receiving party does not need to know the value of the const.