Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

iOS Object-Oriented Swift 2.0 Class Inheritance Overriding Methods

can someone tell me what was my mistake with this subclass

I've provided a base class Person in the editor below. Once an instance of Person is created, you can call getFullName() and get a person's full name.

Your job is to create a class named Doctor that overrides the getFullName() method. Once you have a class definition, create an instance and assign it to a constant named someDoctor.

For example, given the first name "Sam", and last name "Smith", calling getFullName() on an instance of Person would return "Sam Smith", but calling the same method on an instance of Doctor would return "Dr. Smith".

classes.swift
class Person {
    let firstName: String
    let lastName: String

    init(firstName: String, lastName: String) {
        self.firstName = firstName
        self.lastName = lastName
    }

    func getFullName() -> String {
        return "\(firstName) \(lastName)"
    }
}

// Enter your code below
class Doctor: Person {
 override init(firstName: String, lastName: String) {
 super.init(firstName: "Dr.", lastName: "Smith")
 }
 override func getFullName() -> String {
 return "\(firstName) \(lastName)"
 }
 }
 let someDoctor = Doctor(firstName:"Dr.", lastName: "Smith")

1 Answer

You don't need an initializer as Doctor has no new stored properties. Nor do you need to call the superclass's initializer. The purpose of the overriding function was to return something different, viz., "Dr. ---"

// Enter your code below
class Doctor: Person {  

    override func getFullName() -> String {
        return "Dr. \(lastName)"
    }
}

let someDoctor = Doctor(firstName: "Sam", lastName: "Smith")

Finally, when you create a Doctor object you need to give both a first and last name, as you need to fill both of the inherited stored properties.

The difference is that if you call the getFullName() method on a Doctor object like someDoctor you will get back the String "Dr. Smith" rather than "Sam Smith".