Swift 3 Expect Argument Error - swift

Question

I am creating some functions in order to make a game similar to Flappy Bird. I am a complete beginner and am trying to understand everything fully as I go before moving on. I have been able to get my obstacle to move but when I attempt to put it into a function to allow me more flexibility later on with multiple obstacles I receive an error.
'Cannot convert type '()' to expected argument type 'SKAction'
class GameScene : SKScene, SKPhysicsContactDelegate {
var Player = SKSpriteNode()
var Ground = SKSpriteNode()
var Roof = SKSpriteNode()
var Background = SKSpriteNode()
let Obstacle1 = SKSpriteNode(imageNamed: "Fire Barrel 1")
override func didMove(to view: SKView) {
// Create Background Color
backgroundColor = bgColor
// Set World Gravity
self.physicsWorld.gravity = CGVector(dx: 0.0, dy: -4.0)
// Create Player
Player = SKSpriteNode(imageNamed: "Player")
Player.setScale(0.5)
Player.position = CGPoint(x: -self.frame.width / 2 + 100, y: -Player.frame.height / 2)
self.addChild(Player)
// Create Ground
Ground = SKSpriteNode(imageNamed: "BGTileBtm")
Ground.anchorPoint = CGPoint(x: 0,y: 0.5)
Ground.position = CGPoint(x: -self.frame.width / 2, y: -self.frame.height / 2)
self.addChild(Ground)
// Create Roof
Roof = SKSpriteNode(imageNamed: "BGTileTop")
Roof.anchorPoint = CGPoint(x: 1,y: 1)
Roof.position = CGPoint(x: -self.frame.width / 2, y: self.frame.height / 2 - Roof.frame.height)
Roof.zRotation = CGFloat(M_PI)
self.addChild(Roof)
// Set Physics Rules
Player.physicsBody = SKPhysicsBody(texture: SKTexture(imageNamed: "Player"), size: Player.size)
Player.physicsBody!.affectedByGravity = true
Player.physicsBody!.allowsRotation = false
Ground.physicsBody = SKPhysicsBody(texture: SKTexture(imageNamed: "Ground"), size: Ground.size)
Ground.physicsBody!.affectedByGravity = false
Ground.physicsBody!.isDynamic = false
// Obstacle
func addObstacle1(){
Obstacle1.position = CGPoint(x: self.frame.width / 2, y: -self.frame.height / 2 + Obstacle1.frame.height)
Obstacle1.zPosition = 1
addChild(Obstacle1)
}
func moveObstacle1(){
let distance = CGVector(dx: -self.frame.width, dy: 0)
let moveDistance = SKAction.move(by: distance, duration: 5)
run(moveDistance)
}
addObstacle1()
Obstacle1.run(moveObstacle1())
}

Answer 1

Change the declaration of moveObstacle1 to this:
func moveObstacle1() -> SKAction{
let distance = CGVector(dx: -self.frame.width, dy: 0)
let moveDistance = SKAction.move(by: distance, duration: 5)
return moveDistance
}
EDIT:
Regarding your comment,
run is a method. When you call it, it runs the SKAction you passed in. That's it! What you are trying to do is run(moveObstacle1()). What does that mean exactly? How can you pass a method call as a parameter? At runtime, the return value of moveObstacle1() is passed to run. In other words, for run(moveObstacle1()) to compile, moveObstacle1() must return a value using the return statement. And that value must be of type SKAction, since that's the thing you're passing to run.
return is used to return a value from a moveObstacle1(), so that you can call run(moveObstacle1()).
run is just a regular old method.

Answer 2

Change:
Obstacle1.run()
To:
Obstacle1.run(SKAction(moveObstacle1()))
The error message is pretty clear, you need to pass a SKAction to your SKSpriteNode.
Edit
import SpriteKit
import GameplayKit
class GameScene : SKScene, SKPhysicsContactDelegate {
var Player = SKSpriteNode()
var Ground = SKSpriteNode()
var Roof = SKSpriteNode()
var Background = SKSpriteNode()
let Obstacle1 = SKSpriteNode(imageNamed: "Spaceship")
let sprite = SKSpriteNode(imageNamed:"Spaceship")
override func didMove(to view: SKView) {
// Create Background Color
backgroundColor = UIColor.green
// Set World Gravity
self.physicsWorld.gravity = CGVector(dx: 0.0, dy: -4.0)
// Create Player
Player = SKSpriteNode(imageNamed: "Player")
Player.setScale(0.5)
Player.position = CGPoint(x: -self.frame.width / 2 + 100, y: -Player.frame.height / 2)
self.addChild(Player)
// Create Ground
Ground = SKSpriteNode(imageNamed: "BGTileBtm")
Ground.anchorPoint = CGPoint(x: 0,y: 0.5)
Ground.position = CGPoint(x: -self.frame.width / 2, y: -self.frame.height / 2)
self.addChild(Ground)
// Create Roof
Roof = SKSpriteNode(imageNamed: "BGTileTop")
Roof.anchorPoint = CGPoint(x: 1,y: 1)
Roof.position = CGPoint(x: -self.frame.width / 2, y: self.frame.height / 2 - Roof.frame.height)
Roof.zRotation = CGFloat(M_PI)
self.addChild(Roof)
// Set Physics Rules
Player.physicsBody = SKPhysicsBody(texture: SKTexture(imageNamed: "Player"), size: Player.size)
Player.physicsBody!.affectedByGravity = true
Player.physicsBody!.allowsRotation = false
Ground.physicsBody = SKPhysicsBody(texture: SKTexture(imageNamed: "Ground"), size: Ground.size)
Ground.physicsBody!.affectedByGravity = false
Ground.physicsBody!.isDynamic = false
sprite.size = CGSize(width:50, height: 50)
sprite.position = CGPoint(x:self.frame.midX, y:self.frame.midY);
self.addChild(sprite)
Obstacle1.run(SKAction(moveObstacle1()))
}
func moveObstacle1(){
let action = SKAction.moveTo(x: self.frame.size.width * 2, duration: 20)
sprite.run(action)
}
}