How to make enemy have independent lives? - ios

Question

PLEASE HELP!!! I have been trying to figure this out for along time. I have searched the internet and i cannot find anything that will help me.
I am currently making a game in which you are a space ship in the middle and enemy ships are moving towards you and you have to shoot them. some enemies have different lives. for example: a red ship takes one shot to explode, the blue ship takes 3, etc. I have everything to work only the lives. for example: whenever a blue ship is called on to the screen i shoot it once so its life goes down to 2. but whenever a another blue ship is called the first blue ship has its life reset back to 3 again. Is there anyway I can make it so that whenever a ship looses lives it remains that way even if other ships are called ?
this is my ship function that gets called and adds enemy space ships onto the screen:
func VillainRight(){
let TooMuch = self.size.width
let point = UInt32(TooMuch)
life = 3
let VillainR = SKSpriteNode(imageNamed: "BlueVillain")
VillainR.zPosition = 2
VillainR.position = CGPoint(x: self.frame.minX,y: CGFloat(arc4random_uniform(point)))
//This code makes the villain's Zposition point towards the SpaceShip
let angle = atan2(SpaceShip.position.y - VillainR.position.y, SpaceShip.position.x - VillainR.position.x)
VillainR.zRotation = angle - CGFloat(M_PI_2)
let MoveToCenter = SKAction.move(to: CGPoint(x: self.frame.midX, y: self.frame.midY), duration: 15)
//Physics World
VillainR.physicsBody = SKPhysicsBody(rectangleOf: VillainR.size)
VillainR.physicsBody?.categoryBitMask = NumberingPhysics.RightV
VillainR.physicsBody?.contactTestBitMask = NumberingPhysics.Laser | NumberingPhysics.SpaceShip
VillainR.physicsBody?.affectedByGravity = false
VillainR.physicsBody?.isDynamic = true
VillainR.run(MoveToCenter)
addChild(VillainR)
}
This is the code that calls this function:
_ = Timer.scheduledTimer(timeInterval: 5.0, target: self, selector: #selector(Level1.VillainRight), userInfo: nil, repeats: true)
I am using the spritekit in Swift.
Thank You Very Much in advance!

Answer 1

That is happening because life variable is declared as a property of a scene and it is not local to a specific node (enemy ship). You can solve this in a few ways... First way would be using node's userData property:
import SpriteKit
let kEnergyKey = "kEnergyKey"
class GameScene: SKScene, SKPhysicsContactDelegate {
override func didMove(to view: SKView) {
let blueShip = getShip(energy: 3)
let greenShip = getShip(energy: 2)
let redShip = getShip(energy: 1)
if let blueShipEnergy = blueShip.userData?.value(forKey: kEnergyKey) as? Int {
print("Blue ship has \(blueShipEnergy) lives left")
//hit the ship
blueShip.userData?.setValue(blueShipEnergy-1, forKey: kEnergyKey)
if let energyAfterBeingHit = blueShip.userData?.value(forKey: kEnergyKey) as? Int {
print("Blue ship has \(energyAfterBeingHit) lives left")
}
}
}
func getShip(energy:Int)->SKSpriteNode{
//determine which texture to load here based on energy value
let ship = SKSpriteNode(color: .purple, size: CGSize(width: 50, height: 50))
ship.userData = [kEnergyKey:energy]
return ship
}
}
This is what the docs say about userData property:
You use this property to store your own data in a node. For example,
you might store game-specific data about each node to use inside your
game logic. This can be a useful alternative to creating your own node
subclasses to hold game data.
As you can see, an alternative to this is subclassing of a node (SKSpriteNode):
class Enemy:SKSpriteNode {
private var energy:Int
//do initialization here
}