Select multiple nodes while dragging - swift

Question

I'm trying to make a game where the player at certain times draw a pattern on the screen. My solution for this is to add multiple nodes on the screen that are touchable via an extension of SKSpriteNode.
When the player touches a node, I want to call touchesmoved, and add all nodes touched to an array.
Then, when the player stops touching the screen, I want to match that array to another array, and something happens.
I've been playing around with the updates function and try to run a function each update loop, but it didn't work very well. I've also tried making the gameScene class a delegate of my touchableShapeNode Class, but I struggled to make it work.
class TouchableShapeNode: SKShapeNode {
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
if (name != nil) {
print("\(name ?? "node") touched")
}
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
if (name != nil) {
print("\(name ?? "node") touched")
}
}
}
My problem is that the only node that gets selected right now is the first node I touch, not the ones the player's finger move over. Right now I'm just printing the name of the touched node.

Answer 1

I'm not exactly sure what you're after, but here's a little program that does the following:
Puts 15 red blocks on screen
As you drag around the screen, any nodes you touch are added to a set.
When you stop touching, all touched nodes have their colour changed to green.
When you start a new touch, the set of touched nodes is emptied and all nodes return to their starting colour (red).
To use, simply start a new, empty SpriteKit project and replace gameScene.swift with this code.
import SpriteKit
import UIKit
class GameScene: SKScene {
let shipSize = CGSize(width: 25, height: 25)
let normalColour = UIColor.red
let touchedColour = UIColor.green
var touchedNodes = Set<SKSpriteNode>()
override func didMove(to view: SKView) {
let sceneWidth = self.scene?.size.width
let sceneHeight = self.scene?.size.height
// Add 15 colour sprites to the screen in random places.
for _ in 1...15 {
let ship = SKSpriteNode(color: normalColour, size: shipSize)
ship.position.x = CGFloat.random(in: -sceneWidth!/2...sceneWidth!/2) * 0.7
ship.position.y = CGFloat.random(in: -sceneHeight!/2...sceneHeight!/2) * 0.7
ship.name = "ship"
addChild(ship)
}
}
// When the screen is toucheed, empty the 'touchedNodes' set and rest all nodes back to their normal colour.
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
resetTouchedNodes()
}
// As the touch moves, if we touch a node then add it to our 'touchedNodes' set.
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
let touch = touches.first
let location = touch!.location(in: self)
// If there is a node at the touch location, add it to our 'touchedSprites' set.
if let touchedNode = selectNodeForTouch(location) {
touchedNodes.insert(touchedNode)
}
}
// When the touch ends, make all nodes that were touched change colour.
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
for node in touchedNodes {
node.color = touchedColour
}
}
override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {
resetTouchedNodes()
}
// Return the first sprite where the user touched the screen, else nil
func selectNodeForTouch(_ touchLocation: CGPoint) -> SKSpriteNode? {
let nodes = self.nodes(at: touchLocation)
for node in nodes {
if node is SKSpriteNode {
return (node as! SKSpriteNode)
}
}
return nil
}
// Clear the touchedSprites set and return all nodes on screen to their normal colour
func resetTouchedNodes() {
touchedNodes.removeAll()
enumerateChildNodes(withName: "//ship") { node, _ in
let shipNode = node as! SKSpriteNode
shipNode.color = self.normalColour
}
}
}
You could amend this in various ways. For example, you could change the colour of the sprite immediately you touch it in touchesMoved etc.