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iOS Swift 2.0 Protocols Swift 2.0 Protocols Protocols With Methods

Paul Je
Paul Je
4,435 Points
Posted by Paul Je
Paul Je
4,435 Points

Not sure why the protocol can't be the type of WifiLamp

Do the properties embedded in WIfiLamp and the protocol ColorSwitchable have to all be the same? I'm kind of confused and I don't really know what's going on for this chapter, I will see if I have to review some more of the videos again :( I thought I understood but I actually kind of don't. Why isn't the call statement at the end not working? This seems to make sense but I can't spot out why these two problems exist. Thanks for the help in advance !

protocols.swift 
protocol ColorSwitchable {
    func switchColor(color: Color)
}

enum LightState {
    case On, Off
}

enum Color {
    case RGB(Double, Double, Double, Double)
    case HSB(Double, Double, Double, Double)
}

class WifiLamp: ColorSwitchable {
    let state: LightState
    var color: Color

    init() {
        self.state = .On
        self.color = .RGB(0, 0, 0, 0)
    }
}


var changedWifiLight = WifiLamp(state: LightState.On, color: Color.RGB(20.0, 30.0, 50.0, 1.0)
jcorum
jcorum
71,830 Points

Paul, to conform to the protocol you need to implement the method the protocol requires:

class WifiLamp: ColorSwitchable {
    let state: LightState
    var color: Color

    init() {
        self.state = .On
        self.color = .RGB(0,0,0,0)
    }

    func switchColor(color: Color) {
        self.color = color
    }
}

2 Answers

jcorum
jcorum
71,830 Points

Paul, the function switchColor is written not to return anything, so it cannot have a return statement. If it returned a WiFiLamp it would be written this way:

func switchColor(color: Color) -> WifiLamp { . . . }

If you want to test your code in an Xcode playground you can use code like the following;

let wifi1 = WifiLamp()  //create a WifiLamp object
print(wifi1.color)  //display its color
print(wifi1.state)  //display its state

let color1 = Color.RGB(235/255, 122/255, 14/255, 0.5)  //create a Color object
wifi1.switchColor(color1) //call the switchColor() function
print(wifi1.color)  //display the new color

You should get output like this:

RGB(0.0, 0.0, 0.0, 0.0)
On
RGB(0.92156862745098034, 0.47843137254901963, 0.054901960784313725, 0.5)

Here's all the code together in one place:

protocol ColorSwitchable {
    func switchColor(color: Color)
}

enum LightState {
    case On, Off
}

enum Color {
    case RGB(Double, Double, Double, Double)
    case HSB(Double, Double, Double, Double)
}

class WifiLamp: ColorSwitchable {
    let state: LightState
    var color: Color

    init() {
        self.state = .On
        self.color = .RGB(0,0,0,0)
    }

    func switchColor(color: Color) {
        self.color = color
    }
}

let wifi1 = WifiLamp()  //create a WifiLamp object
print(wifi1.color)  //display its color
print(wifi1.state)  //display its state

let color1 = Color.RGB(235/255, 122/255, 14/255, 0.5)  //create a Color object
wifi1.switchColor(color1) //call the switchColor() function with a Color object
print(wifi1.color)  //display the new color
Paul Je
Paul Je
4,435 Points
Paul Je
Paul Je
4,435 Points

This is my code so far, but I can't implement it using your code - I'm not sure how to exactly set the new colour into the method to set the new colour to the lamp, any suggestions?

protocol ColorSwitchable { func switchColor(color: Color) }

enum LightState { case On, Off }

enum Color { case RGB(Double, Double, Double, Double) case HSB(Double, Double, Double, Double) }

class WifiLamp: ColorSwitchable { let state: LightState var color: Color

init(state: LightState, color: Color) {
    self.state = .On
    self.color = .RGB(0, 0, 0, 0)
}

func switchColor(color: Color) {
    self.color = color
    return WifiLamp(state: .On, color: .RGB(20.0, 30.0, 40.0, 1.0))

}

}