Declaring SKSpriteNode outside spawn function returns SIGABRT in Swift - ios

Question

I have a game that I am making where I have a player and an unlimited number of enemies that's spawn at a given position in a certain amount of time. These enemies are shooting bullets at the player. I need to be able to access the Enemy variable outside the SpawnEnemies() function so that I can use it in my SpawnBullets() function. I tried declaring the Enemy variable outside the SpawnEnemies() function but it returned Sigabrt and I don't know how to access the Enemy variable outside the function without getting this error.
Enemy declaration:
var Enemy = SKSpriteNode(imageNamed: "Enemy.png")
SpawnEnemies function:
func SpawnEnemies() {
let MinValue = self.size.width/8
let MaxValue = self.size.width-20
let SpawnPoint = UInt32(MaxValue-MinValue)
self.Enemy.position = CGPoint(x: CGFloat(arc4random_uniform(SpawnPoint)), y: self.size.height)
let action = SKAction.moveToY(-70, duration: 3.0)
self.Enemy.runAction(SKAction.repeatActionForever(action))
self.addChild(Enemy)
}
SpawnBullets function:
func SpawnBullets(){
let Bullet = SKSpriteNode(imageNamed: "bullet.png")
Bullet.zPosition = -5
Bullet.position = CGPointMake(Enemy.position.x, Enemy.position.y)
let action = SKAction.moveToY(self.size.height + 30, duration: 1.0)
Bullet.runAction(SKAction.repeatActionForever(action))
self.addChild(Bullet)
}
Call SpawnEnemies function in didMoveToView():
var EnemyTimer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: Selector("SpawnEnemies"),userInfo: nil, repeats: true)
Call SpawnBullets function in didMoveToView():
var BulletTimer = NSTimer.scheduledTimerWithTimeInterval(0.2, target: self, selector: Selector("SpawnBullets"),userInfo: nil, repeats: true)
I get this error which is a sigabrt but I used a breakpoint to figure out exactly where the error was and what it was:
Attemped to add a SKNode which already has a parent: <SKSpriteNode> name:'(null)' texture:[<SKTexture> 'Enemy.png' (60 x 80)] position:{132, 1024} scale:{1.00, 1.00} size:{60, 80} anchor:{0.5, 0.5} rotation:0.00

Answer 1

Adding children to a scene already is "infinite", you just need to use it to your advantage.
First rework your bullet function like this so that you are passing in an enemy.
func SpawnBullets(enemy : SKSpriteNode){
let Bullet = SKSpriteNode(imageNamed: "bullet.png")
Bullet.zPosition = -5
Bullet.position = CGPointMake(enemy.position.x, enemy.position.y)
let action = SKAction.moveToY(-self.size.height - 70, duration: 1.0)
Bullet.runAction(SKAction.repeatActionForever(action))
self.addChild(Bullet)
}
Then rework your enemy function so that overtime you call it you spawn a new enemy.
func SpawnEnemies() {
var Enemy = SKSpriteNode(imageNamed: "Enemy.png")
Enemy.name = "enemy";
let MinValue = self.size.width/8
let MaxValue = self.size.width-20
let SpawnPoint = UInt32(MaxValue-MinValue)
Enemy.position = CGPoint(x: CGFloat(arc4random_uniform(SpawnPoint)), y: self.size.height)
let action = SKAction.moveToY(-70, duration: 3.0)
Enemy.runAction(SKAction.repeatActionForever(action))
self.addChild(Enemy)
}
In the function didMoveToView, lets add actions to the scene that handles our timing so that we do not use NSTimer
{
...
let spawnEnemy = SKAction.sequence([SKAction.runBlock(
{
[unowned self] in
self.SpawnEnemies();
}),SKAction.waitForDuration(1)]);
let spawnBullet = SKAction.sequence([SKAction.runBlock(
{
[unowned self] in
self.enumerateChildNodesWithName("enemy", usingBlock:
{
(enemy : SKNode,stop: UnsafeMutablePointer <ObjCBool>) in
  self.SpawnBullets(enemy as! SKSpriteNode);
});
}),SKAction.waitForDuration(0.2)]);
let group = SKAction.group([spawnEnemy, spawnBullet])
self.runAction(SKAction.repeatActionForever(group))
}
This code is not tested so let me know if I need to update anything.