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iOS Build a Simple iPhone App with Swift 2.0 Getting Started with iOS Development Swift Recap Part 2

Filip Diarra
Filip Diarra
6,647 Points
Posted by Filip Diarra
Filip Diarra
6,647 Points

Please help solve this challenge on Classes

I cannot for the life of me figure out this challenge. I don't quite grasp how to initialize the subclass properly and what function to write here.

If you could provide an answer with an explanation, that would be AMAZING!

Thank you!

3 Answers

Anjali Pasupathy
Anjali Pasupathy
28,883 Points
Anjali Pasupathy
Anjali Pasupathy
28,883 Points

To subclass a class, you need to use the following format:

class SubClass: ParentClass {
    // DEFINE SUBCLASS PROPERTIES AND METHODS
}

For this challenge, SubClass is Robot, and ParentClass is Machine.

This challenge also asks you to override Machine's move: function. To do this, you write Machine's move: function header with the keyword "override" in front of it, and provide the new implementation for that function inside the body.

class Robot: Machine {
    override func move(direction: String) {
        // PROVIDE NEW IMPLEMENTATION FOR move: HERE
    }
}

The challenge provides instructions for how to implement move. It asks you to use a switch statement to determine whether direction is equal to "Up", "Down", "Left", or "Right", and change the location accordingly. For the default case, the challenge tells you to use the keyword "break".

I hope this helps!

Kyler Smith
Kyler Smith
10,110 Points
Kyler Smith
Kyler Smith
10,110 Points

This one is tricky!!! To make a subclass you need to create the class followed by a colon and the Main class. The class Machine already has a function called move, so you need to override it in your robot class, using the override keyword. In the function, you can either use 'if else' statements or switch statements, I used switch. You want to switch on the String that is being passed in, in our case it is held in the variable 'direction'. Good luck to you!

class Robot: Machine {

    override func move(direction: String) {
       // implement
        }
    }
}
Filip Diarra
Filip Diarra
6,647 Points
Filip Diarra
Filip Diarra
6,647 Points

This helped a lot, thank you!

Why is is that we don't have to override the init nor we have to add the super.init instance here?

Thanks!

Anjali Pasupathy
Anjali Pasupathy
28,883 Points
Anjali Pasupathy
Anjali Pasupathy
28,883 Points

You're welcome! You only need to override init if you're changing what the init does, or adding properties that need to be initialized in the init method. For example, if you added a property called name of type String, you would need to override the init method and call super.init():

class Robot: Machine {
    let name: String

    override init(name: String) {
        self.name = name
        super.init()
    }

    // OVERRIDE NECESSARY METHODS OR ADD METHODS BELOW
}

I hope this helps!