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

Eli MBS
Eli MBS
1,158 Points

Challenge: Build a Simple iPhone App with Swift 2.0

Hey Guys! Would be glad if someone could explain me how this switch here works... I don't get it.

classes.swift
class Point {
    var x: Int
    var y: Int

    init(x: Int, y: Int){
        self.x = x
        self.y = y
    }
}


class Machine {
    var location: Point

    init() {
        self.location = Point(x: 0, y: 0)
    }

    func move(direction: String) {
        print("Do nothing! Im a machine!")
    }
}

// Enter your code below

class Robot: Machine {

    override func move(direction: String) {
        switch ??? {

        case "Up": y += 1

        case "Down": y -= 1

        case "Left": x += 1

        case "Right": x -= 1

        default:
            break
        }
    }
}

2 Answers

David Papandrew
David Papandrew
8,386 Points

Hi Eli,

The switch statement is checking all the cases of the "direction" parameter in the move function. When move is called, a direction needs to be provided (using the object type of "String"). The switch statement then lets you handle all the possible values that the function might provide as input.

Here is how the correct switch statement would look:

class Robot: Machine {

    override func move(direction: String) {
        switch direction {

        case "Up": self.location.y += 1

        case "Down": self.location.y -= 1

        case "Left": self.location.x -= 1

        case "Right": self.location.x += 1

        default:
            break
        }
    }
}
William Crawford
William Crawford
4,319 Points

Thanks, David. I also got stuck here - did not use self.location.y or .x - etc. Thanks!