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iOS Object-Oriented Swift Value vs Reference Types Final Exam - Solution

Im getting the error message use of 'self' in delegating initializer before self.init is called. But why?

This is the code I am using (identical to the one Amit has written in the final exam task:

class Shape {
    let sides: Int
    let name: String

    init(sides: Int, name: String) {
        self.sides = sides
        self.name = name

class Square: Shape {
    var sideLength: Double
    var area: Double {
        get {
            return sideLength * sideLength

        set {
            sideLength = sqrt(newValue)


    init(name: String, sides: Int, sideLength: Double) {
       self.sideLength = sideLength
        super.init(sides: sides, name: name)


    convenience init(sidelength: Double) {
        self.init(name: "Square", sides: 4, sideLength: sideLength) // the error comes up for this line

let square = Square(sidelength: 20)

2 Answers

Chris Shaw
Chris Shaw
26,676 Points

Hi Benjamin,

You have a very minor typo which is causing the error, your parameter name is called sidelength while the variable you're passing to the init declaration is sideLength, notice one has an lowercase L and the other is uppercase. Simply adjust the casing for one of the two and the error will disappear.

Happy coding!

Good eye! I seriously looked through the code so many times, but couldn't find that mistake. Thanks for taking the time!