Objective-C Fundamentals

Accessing existing instance variables
129
Listing 6.5
Creating the init method for the Teacher class
- (id)initWithName:(NSString *)_name
age:(NSNumber *)_age
gender:(Gender)_gender
classes:(NSArray *)_classes
salary:(NSNumber *)_salary
areaOfExpertise:(NSString *)_areaOfExpertise {
if ((self = [super init])) {
name = _name;
age = _age;
gender = _gender;
classes = _classes;
salary = _salary;
areaOfExpertise = _areaOfExpertise;
}
}
return self;
Now you create a similar method for the Student class. The Student initializer takes
the name, age, and gender parameters because it’s a subclass of Person as well, but it
takes slightly different parameters than the Teacher class. Overall, the method is similar
to the Teacher init method, as the following listing shows.
Listing 6.6
Creating the init method for the Student class
- (id)initWithName:(NSString *)_name
age:(NSNumber *)_age
gender:(Gender)_gender
classes:(NSArray *)_classes
numberOfCredits:(NSNumber *)_numberOfCredits
major:(NSString *)_major {
if ((self = [super init])) {
name = _name;
age = _age;
gender = _gender;
classes = _classes;
numberOfCredits = _numberOfCredits;
major = _major;
}
}
return self;
Now that you have all of these methods filled in, you can create Person, Teacher, and
Student objects. Before you start using these classes, let’s look into expanding the
ways you can access all of the attributes of these classes.
6.3 Accessing existing instance variables
You now have these three classes, each with instance variables. You created some initialization
methods to fill in the instance variables, but what do you do if you create a