Objective-C Instance variables

WHYPerson.m

@implementation WHYPerson
...

// This is generated by the compiler (there is no need to put this line in your code)
@synthesize firstName;  // Shorter version

// The above, according to Apple automatic naming convention for instance variables, 
// is just doing this (add '_' prefix):
@synthesize firstName = _firstName;  // Longer version

// Again, in most cases, there is no need to write @synthesize anymore as the compiler does
// it for you automatically. However, if you'd love to, you can name your own instance variable:
@synthesize firstName = _iLoveFancyIVars;  // Custom instance variable naming

// Can also just use a normal name without an underscore prefix
@synthesize firstName = iLoveFancyIvars;

/* Some developers might prefer to do this:
// @synthesize firstName = firstName;
// Yes, this would save the developer having to type "self." every single time but
// I strongly recommend against doing this as it confuses other programmers (especially
// those who are not familiar with the workings of the Objective-C compiler/beginners to the language).
// They might think that [self firstName] == self.firstName == firstName, which, if the getter method is customised,
// would not be the case. It would also discourage new programmers to find out what the difference is between
// the many variable accessor methods.
*/

// And in your methods, you can refer to the variable in a couple of ways
- (void)doSomething {
    NSLog([self firstName]);
    NSLog(self.firstName);  // Just a wrapper for [self firstName]
    NSLog(_firstName);  // Can be done even if you don't put @synthesize as this instance variable is created automatically
    NSLog(_iLoveFancyIvars);  // Can only work if you define a custom instance variable by yourself (line 13)
}

...
@end