Drakalex Drakalex - 4 months ago 18
Swift Question

Optional parameter in class initialization

I'm working with Swift, Sprite-Kit and Xcode 6,

I have a class declared like this :

class Obstacles: SKSpriteNode
{
init(initTime: Int, speed: CGFloat, positionX: CGFloat, rotationSpeed: CGFloat)
{
self.initTime = initTime
self.rotationSpeed = rotationSpeed
self.positionX = positionX

super.init(texture: SKTexture(imageNamed: "Rectangle"), color: SKColor.redColor(), size: CGSize(width: 20, height: 20))
self.speed = speed
}

var initTime: Int
var positionX: CGFloat
var rotationSpeed: CGFloat = 0
}


So I can assign a variable to this class like this :

var myVariable = Obstacles(initTime: 100, speed: 3.0, positionX: 10.0, rotationSpeed: 0.0)


but if for example I don't want to initialize the rotationSpeed value and have it default to 0.0, how can I manage to do so ? I can't remove the parameter, it results me an error...

Answer

What you want is to set a default value for rotationSpeed but you are forgetting to declare the type and assign a default value. Instead of saying rotationSpeed: 0.0) you would have rotationSpeed: CGFloat = 0. Making your initializer look like this:

init(initTime: Int, speed: CGFloat, positionX: CGFloat, rotationSpeed: CGFloat = 0)

You also might find this SO post useful as well