Sprite Kit - Sometimes a ball disappears from the screen?

Question

I am new to sprite pack. I tried a simple ball game with 2 players, the other a slow ball tracking. But I discovered a problem. When I move the line to the ball (with the edge), the ball disappears from the screen. Another time, no problem, the ball bounces. What is the problem?

I have one GameScene, sks and ViewController. My sprite nodes are from sks. If someone explains this case. Will be better. I attached what I did below.

My GameScene:

class GameScene: SKScene {

var ball = SKSpriteNode()
var enemy = SKSpriteNode()
var main = SKSpriteNode()

override func didMove(to view: SKView) {

    ball = self.childNode(withName: "ball") as! SKSpriteNode
    enemy = self.childNode(withName: "enemy") as! SKSpriteNode
    main = self.childNode(withName: "main") as! SKSpriteNode

    ball.physicsBody?.applyImpulse(CGVector(dx: -20, dy: -20))
    ball.physicsBody?.linearDamping = 0
    ball.physicsBody?.angularDamping = 0

    let border = SKPhysicsBody(edgeLoopFrom: self.frame)
    border.friction = 0
    border.restitution = 1

    self.physicsBody = border

}

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {

    for touch in touches {

        let location = touch.location(in: self)
        main.run(SKAction.moveTo(x: location.x, duration: 0.2))
    }
}

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {

    for touch in touches {

        let location = touch.location(in: self)
        main.run(SKAction.moveTo(x: location.x, duration: 0.2))
    }

}

override func update(_ currentTime: TimeInterval) {
    // Called before each frame is rendered

    enemy.run(SKAction.moveTo(x: ball.position.x, duration: 0.5))
}

View controller:

class GameViewController: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()

    if let view = self.view as! SKView? {
        // Load the SKScene from 'GameScene.sks'
        if let scene = SKScene(fileNamed: "GameScene") {
            // Set the scale mode to scale to fit the window
            scene.scaleMode = .aspectFill

            // Present the scene
            view.presentScene(scene)
        }

        view.ignoresSiblingOrder = true


    }
}

override var prefersStatusBarHidden: Bool {
    return true
}

Pad Settings:

Ball Settings:

Some updates

I tried some messages in the update function, and then ran into the same housing ball coming out on the left side of the device (using iPhone 6S)

2016-12-08 14: 27: 54.436485 Pong [14261: 3102941] fatal error: ball from the left borders: file

Answer 1

, . , , / , , . , , .

"" - :

enemy.run(SKAction.moveTo(x: ball.position.x, duration: 0.5))

, , , , . , , , .

, , , ... , , ​​ .

, , , , , .

Answer 2

? update() , , , "". ( , ).

, , , , (.. ) , ( ). , ( ), , "" , - preciseCollisionDetection=true , collisionBitMask.

Answer 3

, ( .update())

if ball.position.x > frame.maxX { fatalError(" ball out of right bounds") }
if ball.position.x < frame.minX { fatalError(" ball out of left bounds") }
if ball.position.y > frame.maxY { fatalError(" ball out of top bounds") }
if ball.position.y < frame.minY { fatalError(" ball out of bottom bounds) }

:

print(ball.position)

, - , - , - .

( ) "fatalError" "ball.position = CGPoint(x: 0, y: 0)" - "reset" .

, , if-statements.

var lastBallLocation = CGPoint(x: 0, y: 0) // Just to initialize
override func update( prams ) {
  if ball.position.x > frame.maxX { ball.position = lastBallLocation }
  // .. copy the other three cases
  lastBallLocation = ball.position // update only on successful position

( node spritenode , , , - "" )

: