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iOS Object-Oriented Swift 2.0 Complex Data Structures Custom Initializers

Matt Smith
Matt Smith
878 Points
Posted by Matt Smith
Matt Smith
878 Points

Have I used Init correct for this challenge? And what is my next step?

What is my next step and why?

structs.swift 
struct RGBColor {
    let red: Double
    let green: Double
    let blue: Double
    let alpha: Double

    let description: String

    // Add your code below
    init(red: Double, green: Double, blue: Double, alpha: Double) {
        self.red = red
        self.green = green
        self.blue = blue
        self.alpha = alpha
    }
}
Art Hayes
Art Hayes
7,251 Points
Art Hayes
Art Hayes
7,251 Points

Hi Matt,

I'm not sure what challenge this is for... but here are a couple of hints.

1) With structs you get 'free' initializers, but if you create your own init you need to initialize ALL of the stored properties in the struct. When you take that into consideration and look up at your code, do you see one problem you might be having?

2) I highly suggest always keeping an open Playground session going in Xcode. It's a fantastic way to learn. (If you plug your code above into a Playground, it'll tell you what the error is) :)

EDIT: Matt - see my answer below.

2 Answers

Filip Diarra
Filip Diarra
6,647 Points
Filip Diarra
Filip Diarra
6,647 Points

I've been stuck on this one for a while now and can't get it to work. My code is:

 init(red: Double, green: Double, blue: Double, alpha: Double, description: String) {
        self.red = red
        self.green = green
        self.blue = blue
        self.alpha = alpha
        self.description = "red: \(red), green: \(green), blue: \(blue), alpha: \(alpha)"
    }

and it still doesn't work. Can you guys help?

Thanks!

Art Hayes
Art Hayes
7,251 Points
Art Hayes
Art Hayes
7,251 Points

Hi Filip,

I had a look at the Challenge... The problem appears to be that you've included the 'description' parameter in the init AND you're setting it within the init as well. Just remove the 'description' parameter from the init and you'll be good to go:

struct RGBColor {
    let red: Double
    let green: Double
    let blue: Double
    let alpha: Double

    let description: String

    init(red: Double, green: Double, blue: Double, alpha: Double) {
    self.red = red
    self.green = green
    self.blue = blue
    self.alpha = alpha

    self.description = "red: \(red), green: \(green), blue: \(blue), alpha: \(alpha)"

    }
}
Filip Diarra
Filip Diarra
6,647 Points
Filip Diarra
Filip Diarra
6,647 Points

Hey Art,

Thanks for the answer! I don't understand why do we have to initialize the colors, but we don't initialize the description? I thought if I don't initialize the description, it won't work. Could you explain how come it works without being initialized?

Thanks!

Art Hayes
Art Hayes
7,251 Points
Art Hayes
Art Hayes
7,251 Points

Sure, I think here's where you're confused... you don't init items in this line:

init(red: Double, green: Double, blue: Double, alpha: Double) {

This is where you're bringing in the parameters from within the application... but you are initializing the properties INSIDE the init brackets { }

Have a look in the brackets - you are setting all the properties there!

Here's another example... this is valid code as well (though it's not very useful in the real world)...

We're initializing the properties inside the init (but now you won't be able to send arguments into the init now when you initialize this struct because we removed the parameters from the init!)

struct RGBColor {
    let red: Double
    let green: Double
    let blue: Double
    let alpha: Double

    let description: String

    init() {
        self.red = 30
        self.green = 210
        self.blue = 0
        self.alpha = 1

        self.description = "red: \(red), green: \(green), blue: \(blue), alpha: \(alpha)"

    }
}