Difference between Nil , nil and NULL

Difference between Nil , nil and NULL

nil is a null pointer to an Objective-C object

Nil is a null pointer to an Objective-C class. 

NULL is  a null pointer to anything else

 Actually all the three have the numeric value of 0.

• nil == (id) 0 
• Nil == (Class) 0 
• NULL == (void *) 0 

simply can say that nil is a pointer to an object

    for example : 

     NSArray *array = [NSArray arrayWithObjects:@"karthik", @"prabhu", nil];