Ray Wenderlich Functions and Types Course - Part 10

Last chapter! The course suddenly got a lot harder with properties and methods so hopefully this will be accessible. Then it will be the consolidation one!

Start Time - 17:47

Inheritance

For classes, inheritance is something I've used before.

class Person {

  var firstName: String

  var lastName: String

  

  init(firstName: String, lastName: String) {

    self.firstName = firstName

    self.lastName = lastName

  }

}

class Student: Person {

  var grades: [Grade] = []

  

  

}

let bob = Student(firstName: "Bob", lastName: "Stevens")

All of that is fine. The super and sub class etc.

Person is a base class and student inherits from that. Person could have as many sub classes as necessary. You can subclass from a subclass.

Paused for approx 25 minutes.

Polymorphism - a subclass can be treated as its own type or one of its superclasses.

This links to casting too - up and down casting. Use of the as keyword.

Examples about casting -

let dude2 = dude as! StudentAthlete

func getActivity(student: Student) -> String {

    

    if let athleteMember = student as? StudentAthlete {

        return " \(athleteMember) is practising for the team!"

    } else {

        return "Not eligible"

    }

}

getActivity(student: dude)

Also, there is making computed property with override. 

Challenge!

Paused at 18:50; restart at 20:47

Finished challenges! Actually I think I've smashed them...let's see!

Finished at 20:57 (total time approx 45 minutes)

So a good session. All about inheritance with some computed properties and other concepts brought back in. The fact that I did the challenge without too many difficulties is a really good sign! More tomorrow!