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iOS Object-Oriented Swift 2.0 Complex Data Structures Custom Initializers

Posted by Paul Zhang
Paul Zhang
464 Points

Could not pass last task in oop swift

It is the task of creating RGBColor init function. I tested my code and printed out the result. It matches the required outcome. But it keeps saying the value of description does not match. Can someone help me check? Thanks.

PS. I tried both with or without double quotes.

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

        description = String(format:"red: %.1f, green: %.1f, blue: %.1f, alpha: %.1f", red, green, blue, alpha)
    }
}

3 Answers

Ayso Lima Marques
Ayso Lima Marques
5,122 Points
Ayso Lima Marques
Ayso Lima Marques
5,122 Points

write that way:

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

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


}
Paul Zhang
Paul Zhang
464 Points

Hi Ayso, your change worked. But why?

Ayso Lima Marques
Ayso Lima Marques
5,122 Points
Ayso Lima Marques
Ayso Lima Marques
5,122 Points

i'm not sure about it, cause i'm not that experienced with swift, but i think that u missed the "self." in the description initializer, and that your syntax it's more proper to objective - c, in swift it's more appropriate use string interpolation 

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

Since you don't use the "self." you're not referring to the property "description" that's outside the init

Paul Zhang
Paul Zhang
464 Points

No, self. is not the issue (tried and it failed as well).

It seems the tutorial is forcing us to use string interpolation and completely drop the back compatible ways.

But it would be hard to control the precision and I read from Swift Recipes: A Problem-Solution Approach:

"Note: When converting a Float to a string, you may see unpredictable results dueo to the binary representation of values. If this occurs, use NSString(format: "%.02f", str) to control the precision."

Thanks for your reply and I will move on.

Ayso Lima Marques
Ayso Lima Marques
5,122 Points
Ayso Lima Marques
Ayso Lima Marques
5,122 Points

you're welcome, and yes, the treehouse's editor is limited, it aways expects us to solve the problem in a way equal or similar that is explained in the videos