How can I move sprites around with my finger? - ios

Question

I want to be able to move a sprite with my finger. I first have a variable for whether the finger is on the sprite or not:
var isFingerOnGlow = false
Then I have the touchesBegan function where I change the value of the above variable if the user touches the sprite:
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
var touch = touches.anyObject() as UITouch!
var touchLocation = touch.locationInNode(self)
if let body = physicsWorld.bodyAtPoint(touchLocation) {
if body.node!.name == GlowCategoryName {
println("Began touch on hero")
isFingerOnGlow = true
}
}
}
Sometimes it works, and the console displays "began touch on hero", sometimes not. Is there a better way to code this first part?
Then I wonder if my following code for touchesMoved is effective:
override func touchesMoved(touches: NSSet, withEvent event: UIEvent) {
if isFingerOnGlow{
var touch = touches.anyObject() as UITouch!
var touchLocation = touch.locationInNode(self)
var previousLocation = touch.previousLocationInNode(self)
var glow = SKSpriteNode(imageNamed: GlowCategoryName)
// Calculate new position along x for glow
var glowX = glow.position.x + (touchLocation.x - previousLocation.x)
var glowY = glow.position.y + (touchLocation.y - previousLocation.y)
// Limit x so that glow won't leave screen to left or right
glowX = max(glowX, glow.size.width/2)
glowX = min(glowX, size.width - glow.size.width/2)
glow.position = CGPointMake(glowX, glowY)
}
}
...
override func touchesEnded(touches: NSSet, withEvent event: UIEvent) {
isFingerOnGlow = false
}

Answer 1

You can modify the functions like this to track the touches.
var isFingerOnGlow = false
var touchedGlowNode : SKNode!
override func touchesBegan(touches: NSSet, withEvent event:UIEvent) {
var touch = touches.anyObject() as UITouch!
var touchLocation = touch.locationInNode(self)
let body = self.nodeAtPoint(touchLocation)
if body.name == GlowCategoryName {
println("Began touch on hero")
touchedGlowNode = body
isFingerOnGlow = true
}
}
override func touchesMoved(touches: NSSet, withEvent event: UIEvent) {
if isFingerOnGlow{
let touch = touches.anyObject() as UITouch!
let touchLocation = touch.locationInNode(self)
let previousLocation = touch.previousLocationInNode(self)
let distanceX = touchLocation.x - previousLocation.x
let distanceY = touchLocation.y - previousLocation.y
touchedGlowNode.position = CGPointMake(touchedGlowNode.position.x + distanceX,
touchedGlowNode.position.y + distanceY)
}
}
override func touchesEnded(touches: NSSet, withEvent event: UIEvent) {
isFingerOnGlow = false
}