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iOS

william fashanu
william fashanu
2,108 Points
Posted by william fashanu
william fashanu
2,108 Points

I dont know how to tackle this question

In the editor, I’ve declared a struct named RGBColor that models a color object in the RGB space.

Your task is to write a custom initializer method for the object. Using the initializer assign values to the first four properties. Using the values assigned to those properties create a value for the description property that is a string representation of the color object.

For example, given the values 86.0 for red, 191.0 for green, 131.0 for blue and 1.0 for alpha, each of the stored properties should hold these values and the description property should look like this:

"red: 86.0, green: 191.0, blue: 131.0, alpha: 1.0"

Note: Init methods typically list parameters in the same order of property declaration. For this task, stick to the order red,green,blue,alpha.

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

let description: String

// Add your code below

}

3 Answers

Tassia Castro
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.a{fill-rule:evenodd;}techdegree
Tassia Castro
iOS Development Techdegree Student 9,170 Points
Tassia Castro
.a{fill-rule:evenodd;}techdegree
Tassia Castro
iOS Development Techdegree Student 9,170 Points

Hi Willian,

Try this..

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

Hope this helps.

william fashanu
william fashanu
2,108 Points
william fashanu
william fashanu
2,108 Points

thank you can you explain the init method to me i dont quite understand it fully and its purpose

Tassia Castro
seal-mask
.a{fill-rule:evenodd;}techdegree
Tassia Castro
iOS Development Techdegree Student 9,170 Points
Tassia Castro
.a{fill-rule:evenodd;}techdegree
Tassia Castro
iOS Development Techdegree Student 9,170 Points

Hi Willian,

The init method is simply used to assign values to the properties of the classes.

As you can see, we have a struct in this example. Structs receive a init method automatically. So this code would also work:

struct RGBColor {
    let red: Double
    let green: Double
    let blue: Double
    let alpha: Double
    let description: String
}

When you tried to create an instance of RGBColor, swift would use the automatic init and you would be able to initialise it like that.

var color = RGBColor(red: 86.0, green: 191.0, blue: 131.0, alpha: 1.0, description: "red: 86.0, green: 191.0, blue:131.0, alpha:1.0") //automatic init

But if I am not mistaken one of the main reasons of this exercise is to make us use string interpolation. For this reason, we had to create a custom initialiser that does not receive the property description but Instead we have to create the value of the property description using the values that are being passed through the init.

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 = "red: \(red), green: \(green), blue: \(blue), alpha: \(alpha)" // this is string interpolation, when you concatenate string with a variable.
    }
}

We have to agree that the second version is better. With the automatic init, every time I create an instance of RGBColor I have to pass all the values by myself to the description property. However with the custom init, the property description is always initialised for me.

var color = RGBColor(red: 86.0, green: 191.0, blue: 131.0, alpha: 1.0) //custom init

Hope this helps.

Adrian Torrente Tenreiro
Adrian Torrente Tenreiro
12,540 Points
Adrian Torrente Tenreiro
Adrian Torrente Tenreiro
12,540 Points

The Compilator is always driving me crazy as sometimes it works the way i do it but its not set up for all possibilites