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

Ryan Maneo
Ryan Maneo
4,342 Points

Lost

I totally get what he's trying to do but I seem to have forgotten the syntax to do so, for the if instructions I would obviously use "if" and "else if" but I forgot how to pass in certain strings to return certain tasks... grrr!!!

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! I'm a machine!")
    }
}

/* Enter your code below


class Robot: Machine {

override func [What do I name it?](// What do I put for paramaters here?) {

if this then that?
else if this then that?

}

}
Super confused, help!
*/

2 Answers

You need to override the move method, which in Machine just prints. You need a switch statement to switch on the direction being passed in as a parameter to the method. As the instructions say, the directions are either Up, Down, Left or Right. For each direction you need to increment or decrement the x or y value of location:

class Robot: Machine {
    override func move (direction: String) {
        switch direction {
        case "Up":
            self.location.y++
        case "Down":
            self.location.y--
        case "Left":
            self.location.x--
        case "Right":
            self.location.x++
        default: break
        }
    }
}

Note, you must have a default for the switch. Although location.y += 1 is the same as location.y++, the editor won't take the former.

Ryan Maneo
Ryan Maneo
4,342 Points

Still nope... error is: swift_lint.swift:22:45: error: function produces expected type 'String'; did you mean to call it with '()'? print("Do nothing! I'm a machine!") { ^

One thing I forgot to mention is that if you don't remove the apostrophe from this line:

print("Do nothing! I'm a machine!")

your code will not be colored correctly in the editor. It will look like a big comment (all orange). But the editor will still accept it.

I also didn't answer two of the questions in your code: What do I name it? What do I put for parameters?

When you override you are either replacing or revising an inherited function. You must name the overriding function exactly the same as the function you are overriding, and it must have exactly the same method signature (number and type of parameters).

Not sure why you are getting the error you report. If you copy my code above, and paste it directly under this comment: // Enter your code below it should work fine. I just tried it again, and got no error message.

The error you report is very puzzling, as this code doesn't call any function. Are you trying to call the move() function somewhere?

Hope this helps.