Class with defined static constant values in Objective-C

Question

I want to create a class that will contains static values accessable from all project.

Pseudocode:

class Constants:
  constant String API_URL : "http://api.service.com"
  constant Integer SOME_VALUE : 7

How can I do this with Objective-C ?

Answer 1

Answer for your question is extern keyword . I will explain it to you using an example . Add objective c classes your project and name them Common , Now in Common.h

     @interface Common : NSObject

     extern NSString *SiteApiURL;

     @end

After you defined an instance of NSString Class using the extern keyword what you need to do is switch to Common.m class and initialize the value for NSString (SiteApiURL)

     #import "Common.h"

     @implementation Common

     NSString *SiteApiURL = @"http://api.service.com";

     @end

Import the Common.h class within the project-Prefix.pch file like this

    #import <Availability.h>

    #ifndef __IPHONE_3_0
    #warning "This project uses features only available in iOS SDK 3.0 and later."
    #endif

    #ifdef __OBJC__
        #import <UIKit/UIKit.h>
        #import <Foundation/Foundation.h>
        #import "Common.h"
    #endif

All done , now you can use the object "SiteApiURL" anywhere in the whole project and you need not to import any class anywhere i.e. You can use this variable anywhere in the project directly.