Objective C is programming language developed by adding object orientation to C programming. A basic hello world example is shown below.

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[])
{

    @autoreleasepool {
        
        // insert code here...
        NSLog(@"Hello, World!");
        
    }
    return 0;
}

On running the above program, you get an output as shown below.

2014-04-22 22:19:36.546 eezySample[875:303] Hello, World!

Procedure for creating a sample Xcode project for Objective-C

  1. Open Xcode.
  2. Select File -> New.
  3. Select OS X Application tab.
  4. Select Command Line Tool. Press Next.
  5. Enter Project Name, Organization Name and Company Identifier and press Next.
  6. Select location to save and select Create.

Basic structure of Objective C

In Objective C, we use interface and implementation as building blocks for creating classes. Read all the Objective C links here to know more.

/* Use import for including Objective C 
classes */
#import <Foundation/Foundation.h>

// Single line comment in Objective C
/* Multi Line comment in 
Objective C */

// Interface  for class with class name eezySampleClass
@interface EezySampleClass:NSObject /* NSObject is 
super class of all Objective C classes*/
{
 // Instance variables
}

// Class properties
// Instance methods declarations

@end

// Implementation
@implementation EezySampleClass

// Instance method definitions

@end

/* Every Objective C applications have a main 
and allows command line arguments */
int main(int argc, const char * argv[])
{
/*  Autoreleasepool used in main for 
automatic memory management.*/
    @autoreleasepool {
        
        // A simple log
        NSLog(@"Hello, World!");
		EezySampleClass *eezySampleClass = 
			[[EezySampleClass alloc] init];
        NSLog(@"%@",[eezySampleClass class]);

    }
    return 0;
}

On running the above program, you get an output as shown below.

2014-04-22 22:44:32.407 eezySample[903:303] Hello, World!
2014-04-22 22:44:32.410 eezySample[903:303] EezySampleClass

Don't worry, if you find the above as confusing. You will understand as you go along as others pages are light in content.