How to recognize continuous touch in Swift?

Question

How can I recognize continuous user touch in Swift code? By continuous I mean that the user has her finger on the screen. I would like to move a sprite kit node to the direction

Answer 1

The basic steps

1. Store the location of the touch events (touchesBegan/touchesMoved)
2. Move sprite node toward that location (update)
3. Stop moving the node when touch is no longer detected (touchesEnded)

Here's an example of how to do that

Xcode 8

let sprite = SKSpriteNode(color: SKColor.white, size: CGSize(width:32, height:32))
var touched:Bool = false
var location = CGPoint.zero

override func didMove(to view: SKView) {
    /* Add a sprite to the scene */
    sprite.position = CGPoint(x:0, y:0)
    self.addChild(sprite)
}

override func touchesBegan(_ touches: Set, with event: UIEvent?) {
    touched = true
    for touch in touches {
        location = touch.location(in:self)
    }
}

override func touchesMoved(_ touches: Set, with event: UIEvent?) {
    for touch in touches {
        location = touch.location(in: self)
    }
}

override func touchesEnded(_ touches: Set, with event: UIEvent?) {
    // Stop node from moving to touch
    touched = false
}

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

// Move the node to the location of the touch
func moveNodeToLocation() {
    // Compute vector components in direction of the touch
    var dx = location.x - sprite.position.x
    var dy = location.y - sprite.position.y
    // How fast to move the node. Adjust this as needed
    let speed:CGFloat = 0.25
    // Scale vector
    dx = dx * speed
    dy = dy * speed
    sprite.position = CGPoint(x:sprite.position.x+dx, y:sprite.position.y+dy)
}

Xcode 7

let sprite = SKSpriteNode(color: SKColor.whiteColor(), size: CGSizeMake(32, 32))
var touched:Bool = false
var location = CGPointMake(0, 0)

override func didMoveToView(view: SKView) {
    self.scaleMode = .ResizeFill
    /* Add a sprite to the scene */
    sprite.position = CGPointMake(100, 100)
    self.addChild(sprite)
}

override func touchesBegan(touches: Set, withEvent event: UIEvent?) {
    /* Start moving node to touch location */
    touched = true
    for touch in touches {
        location = touch.locationInNode(self)
    }
}

override func touchesMoved(touches: Set, withEvent event: UIEvent?) {
    /* Update to new touch location */
    for touch in touches {
        location = touch.locationInNode(self)
    }
}

override func touchesEnded(touches: Set, withEvent event: UIEvent?) {
    // Stop node from moving to touch
    touched = false
}

override func update(currentTime: CFTimeInterval) {
    /* Called before each frame is rendered */
    if (touched) {
        moveNodeToLocation()
    }
}

// Move the node to the location of the touch
func moveNodeToLocation() {
    // How fast to move the node
    let speed:CGFloat = 0.25
    // Compute vector components in direction of the touch
    var dx = location.x - sprite.position.x
    var dy = location.y - sprite.position.y
    // Scale vector
    dx = dx * speed
    dy = dy * speed
    sprite.position = CGPointMake(sprite.position.x+dx, sprite.position.y+dy)

}