Objective-C Use ivars in init

WHYPerson.m

@implementation WHYPerson

- (id)init {
    self = [super init];
    
    if (self) {
        // It is recommended to use instance variables directly to initialise the object
        _firstName = ...;
        _lastName = ...;
        _dateOfBirth = ...;
    }
    
    return self;
}

- (void)doSomething {
    // We use message-passing to access properties in methods that are not responsible to initialise the object
    NSLog([self firstName]);
}

...
@end