Spritekit : how to make newly spawned enemy ships shoot bullets at player? - ios

Question

I need help with coming up with ways to make to make the newly spawned enemy ships all shoot bullets. The problem is that I don't actually know how I am going to do that. I tried using a variable timer but, it only shoots one straight line and I can't really control the location it spawns at.
Game Picture: There are more enemies spawning
What I Tried:
var EnemyTimer = Foundation.Timer.scheduledTimer(timeInterval: 0.3, target: self, selector: #selector(GameScene.spawnBullet3), userInfo: nil, repeats: true)
Also Tried:
}
func spawnBullet3(){
let Bullet = SKSpriteNode(imageNamed: "eBullet.png")
Bullet.setScale(1)
Bullet.zPosition = -1
Bullet.position = CGPoint(x: enemy.position.x, y: enemy.position.y)
let action = SKAction.moveTo(y: self.size.height + 100, duration: 0.5)
let actionDone = SKAction.removeFromParent()
Bullet.run(SKAction.sequence([action, actionDone]))
Bullet.physicsBody = SKPhysicsBody(rectangleOf: Bullet.size)
Bullet.physicsBody?.categoryBitMask = PhysicsCategories.Bullet
Bullet.physicsBody!.collisionBitMask = PhysicsCategories.None
Bullet.physicsBody?.contactTestBitMask = PhysicsCategories.Enemy
Bullet.physicsBody?.affectedByGravity = true
Bullet.physicsBody?.isDynamic = false
self.addChild(Bullet)
}

Answer 1

Well, for starters, (as LearnCocos2D explained wonderfully here) never user a Timer, performSelector:afterDelay:, or Grand Central Dispatch (GCD, ie any dispatch_... method.
Before anything, you must set up a couple of things:
First, replace add an argument to your spawnBullet3 function (If you use a custom class replace enemy:SKSpriteNode with enemy:yourCustomClass).
func spawnBullet3(enemy:SKSpriteNode){
let Bullet = SKSpriteNode(imageNamed: "eBullet.png")
Bullet.setScale(1)
Bullet.zPosition = -1
Bullet.position = CGPoint(x: enemy.position.x, y: enemy.position.y)
let action = SKAction.moveTo(y: self.size.height + 100, duration: 0.5)
let actionDone = SKAction.removeFromParent()
Bullet.run(SKAction.sequence([action, actionDone]))
Bullet.physicsBody = SKPhysicsBody(rectangleOf: Bullet.size)
Bullet.physicsBody?.categoryBitMask = PhysicsCategories.Bullet
Bullet.physicsBody!.collisionBitMask = PhysicsCategories.None
Bullet.physicsBody?.contactTestBitMask = PhysicsCategories.Enemy
Bullet.physicsBody?.affectedByGravity = true
Bullet.physicsBody?.isDynamic = false
self.addChild(Bullet)
}
Second, create a public enemies array (Again, if you use a custom class replace SKSpriteNode with your custom class name).
var enemies:[SKSpriteNode] = []
Next, every time you create a new enemy, append the enemy to the array
enemies.append(newEnemy)
Now you have two options:
Option 1: Use a SKAction
Use a SKAction timer to automate every enemy shooting every couple of seconds (Replace SKAction.waitForDuration(2.5) with SKAction.waitForDuration(yourAmountOfSeconds)).
for e in enemies
{
var wait = SKAction.waitForDuration(2.5)
var run = SKAction.runBlock {
spawnBullet3(e)
}
e.runAction(SKAction.repeatActionForever(SKAction.sequence([wait, run])))
}
Option 2: Use the update function
Use the currentTime from the update function (Replace currentTime.truncatingRemainder(dividingBy: 3) with currentTime.truncatingRemainder(dividingBy: yourAmountOfSeconds)).
override func update(_ currentTime: TimeInterval) {
[...]
if currentTime.truncatingRemainder(dividingBy: 3) == 0
{
for e in enemies
{
spawnBullet3(e)
}
}
}