Move a sprite randomly using Swift 3 - swift

Question

I was trying to make a game where the dragon moves around randomly and the hero has to avoid it. I can make the dragon appear at a random location and move once or twice but to make it continuously move from point to point and then move some more has given me trouble. I think it might be because I'm not waiting for the action to complete before generating all of the random numbers. I tried the following code including labels to prove to myself that the random numbers are generating, at least up to 20...
import SpriteKit
import GameplayKit
class GameScene: SKScene {
private let greenDragonNode = GreenDragonSprite.newInstance()
private var lastUpdateTime : TimeInterval = 0
private var i = 0
override func sceneDidLoad() {
self.lastUpdateTime = 0
let xOrigin = CGFloat(arc4random()).truncatingRemainder(dividingBy: size.width)
let yOrigin = CGFloat(arc4random()).truncatingRemainder(dividingBy: size.height)
let dragonOrigin = CGPoint(x: xOrigin, y: yOrigin)
greenDragonNode.position = dragonOrigin
greenDragonNode.setScale(0.1)
addChild(greenDragonNode)
}
override func didMove(to view: SKView) {
for i in 1...20 {
let xDestination = CGFloat(arc4random()).truncatingRemainder(dividingBy: size.width)
let yDestination = CGFloat(arc4random()).truncatingRemainder(dividingBy: size.height)
let dragonDestination = CGPoint(x: xDestination, y: yDestination)
let xDestination2 = CGFloat(arc4random()).truncatingRemainder(dividingBy: size.width)
let yDestination2 = CGFloat(arc4random()).truncatingRemainder(dividingBy: size.height)
let dragonDestination2 = CGPoint(x: xDestination2, y: yDestination2)
let dragonNodeTravel = SKAction.move(to:dragonDestination, duration: 3.0)
let dragonNodeReturn = SKAction.move(to: dragonDestination2, duration: 3.0)
greenDragonNode.run(SKAction.sequence([dragonNodeTravel, dragonNodeReturn]))
// i += 1
let label = SKLabelNode(text: "\(i)")
label.position = dragonDestination2
addChild(label)
}
}
}

Answer 1

That is happening because only the last action from the for loop is executed. You have to make a queue of actions. So you should append them to an array, and run them in a sequence, like this:
import SpriteKit
import GameplayKit
class GameScene: SKScene {
private let greenDragonNode = SKSpriteNode(color: .green, size: CGSize(width: 20, height: 20))
func getRandomPoint(withinRect rect:CGRect)->CGPoint{
let x = CGFloat(arc4random()).truncatingRemainder(dividingBy: rect.size.width)
let y = CGFloat(arc4random()).truncatingRemainder(dividingBy: rect.size.height)
return CGPoint(x: x, y: y)
}
override func didMove(to view: SKView) {
greenDragonNode.position = self.getRandomPoint(withinRect: frame)
addChild(greenDragonNode)
var actions:[SKAction] = []
for i in 1...20 {
let destination = getRandomPoint(withinRect: frame)
let move = SKAction.move(to:destination, duration: 1.0)
actions.append(move)
let label = SKLabelNode(text: "\(i)")
label.position = destination
addChild(label)
}
let sequence = SKAction.sequence(actions)
greenDragonNode.run(sequence)
}
}