I keep getting an error saying "expected declaration" - swift

Question

I'm following a tutorial to make a version of flappy bird. I'm using swift and this error keeps coming up. The "addChild(self.myFloor1) keeps saying expected declaration error. What did I do wrong?
import SpriteKit
class GameScene: SKScene, SKPhysicsContactDelegate {
var myBackground = SKSpriteNode()
var myFloor1 = SKSpriteNode()
var myFloor2 = SKSpriteNode()
addChild(self.myFloor1)
override func didMoveToView(view: SKView) {
myBackground = SKSpriteNode(imageNamed: "background")
myBackground.anchorPoint = CGPointZero;
myBackground.position = CGPointMake(100, 0);
self.backgroundColor = SKColor(red: 80.0/255.0, green: 192.0/255.0, blue: 203.0/255.0, alpha: 1.0)
addChild(self.myBackground)
myFloor1 = SKSpriteNode(imageNamed: "floor")
myFloor2 = SKSpriteNode(imageNamed: "floor")
myFloor1.anchorPoint = CGPointZero;
myFloor1.position = CGPointMake(0, 0);
myFloor2.anchorPoint = CGPointZero;
myFloor2.position = CGPointMake(myFloor1.size.width-1, 0);
}
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
}
override func update(currentTime: CFTimeInterval) {
/* Called before each frame is rendered */
}
}

Answer 1

When you write
addChild(self.myFloor1)
You are calling a method, which must be done inside another method declaration.
Within your class declaration, the "highest level" "things" need to be declared as something: "var", "let", "func". Then within a "func", you can call your addChild method.
That's why you are getting the error: At that "class" level, it's expecting only things that you can specify what they are. Which here, you are not. You are trying to directly call that method.
What I suspect you may want, is add the viewDidLoad method and call addChild from within there. Or something like that...whatever makes sense for your view lifecycle.

Answer 2

Declaration refers to creating a new variable or method. The location you wrote addChild() seems as if you're creating a new variable. For example, let's look at the following simple class.
class GameScene: SKScene {
var myBackground = SKSpriteNode()
}
The variable myBackground is being declared as a new variable. You are creating a new instance of an SKSpriteNode object. SKSpriteNode is also a class. Now let's add a method to your GameScene class that prints hello. All the things you declare in the class is referred as being in the top level, which is where you create variables and functions, etc.
class GameScene: SKScene {
var myBackground = SKSpriteNode()
//This is a method/function of the class GameScene
func sayHello() {
print("Hello.")
}
//CAN'T CALL ITS OWN METHOD AT THE TOP LEVEL
sayHello()
}
To help you understand, addChild is a method/function of the SKNode class.
class SKNode: UIResponder {
func addChild(node: SKNode) {...}
}
So when you have something like you have it, it doesn't make sense because addChild is a function and you can't call a function at the top level of a class.
class GameScene: SKScene {
var myBackground = SKSpriteNode()
var myFloor1 = SKSpriteNode()
//CAN'T CALL METHOD ON TOP LEVEL OF CLASS
addChild(self.myFloor1)
}
Xcode thinks you're creating a new function called addChild, so it's expecting you to declare it by using the "func" keyword, which is why it's giving you the error, but obviously you're not creating a function call addChild, you need to call it.
You have to call addChild() inside a function/method because it calls the SKNode's addChild method.