I'm working in Swift with Sprite-Kit using XCode 6, and I have many different nodes but for the moment I only manage to detect one finger and move one node at the same time. I want to know how could I manage to detect multiple fingers in order to move multiple nodes at the same time. My actual code is :
var location = CGFloat() // finger position
var actualNode = -1 // node touched by the finger, -1 means no node touched
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) // when a finger touch the screen
{
for touch: AnyObject in touches
{
location = touch.locationInNode(self) // we detect the finger position
}
for var index = 0; index < colorNode.count; index++
{
if nodeAtPoint(location) == colorNode[index].node
{
actualNode = index // the number of the node touched by the finger
}
}
}
override func touchesMoved(touches: NSSet, withEvent event: UIEvent) // when a finger move
{
for touch: AnyObject in touches
{
location = touch.locationInNode(self) // we detect the finger position
}
if actualNode != -1 // if a node is touched
{
colorNode[actualNode].position = location // we move this node to the finger
}
}
override func touchesEnded(touches: NSSet, withEvent event: UIEvent) // when a finger don't touch the screen anymore
{
actualNode = -1 // there is no node touched
}
As you can see I only have the position
of my first finger, but how can I detect multiple finger position and assign each finger to the node touched by the finger ?
Moving multiple nodes simultaneously is fairly straightforward. The key is to track each touch event independently. One way to do that is to maintain a dictionary that uses the touch event as the key and the node being moved as the value.
First, declare the dictionary
var selectedNodes:[UITouch:SKSpriteNode] = [:]
Add each sprite touched to the dictionary with the touch event as the key
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches {
let location = touch.location(in:self)
if let node = self.atPoint(location) as? SKSpriteNode {
// Assumes sprites are named "sprite"
if (node.name == "sprite") {
selectedNodes[touch] = node
}
}
}
}
Update the positions of the sprites as needed
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches {
let location = touch.location(in:self)
// Update the position of the sprites
if let node = selectedNodes[touch] {
node.position = location
}
}
}
Remove the sprite from the dictionary when the touch ends
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches {
if selectedNodes[touch] != nil {
selectedNodes[touch] = nil
}
}
}