Dragging 1 sprite node relevant to finger movement? - ios

Question

I have created a node called and i have amanged to make it drag from across the screen when the node it touched and dragged. For some reason this one method (code below) lets me drap any node on the screen. How can i make effect only the one "testNode2".
Also i would the node to drag to the movement of the finger but this can work if the finger is touch anywhere on the screen, not just when the node itself is touched? (but not jump to the position of the finger, just move relevant to the finger movement). For example is the screen is pressed anywhere then dragged 100 pixels left the node will move 100 pixels left.
my code is below
-(void) colourSprite2:(CGSize)size {
self.testNode2 = [SKSpriteNode spriteNodeWithColor:[SKColor greenColor] size:CGSizeMake(30, 30)];
self.testNode2.position = CGPointMake(self.size.width/2, self.size.height/1.1);
self.testNode2.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:self.testNode2.frame.size];
[self addChild:self.testNode2];
}
-(void)touchesBegan:(NSSet*) touches withEvent:(UIEvent*) event
{ self.testNode2 = [self nodeAtPoint:[[touches anyObject] locationInNode:self]]; }
-(void)touchesMoved:(NSSet*) touches withEvent:(UIEvent*) event
{ self.testNode2.position = [[touches anyObject] locationInNode:self]; }
-(void)touchesEnded:(NSSet*) touches withEvent:(UIEvent*) event
{ self.testNode2 = nil; }

Answer 1

The touch delegate returns an NSSet of touches which holds multiple UITouch objects, each of which correspond to a touch relevant to the object the delegate methods are implemented in.
In your case, the node will move itself to the position of any touch the delegate encounters. This includes multiple touches on the screen.
You should read about UITouch and the UIResponder classes.
The solution for your problem will be to keep a track of the specific touch that is being used to move the node.
Maintain a UITouch object as an instance variable:
#implementation MyScene
{
UITouch *currentTouch;
}
Then keep a track of the specific touch as follows:
-(void)touchesBegan:(NSSet*) touches withEvent:(UIEvent*) event
{
UITouch *touch = [touches anyObject];
SKNode *node = [self nodeAtPoint:[touch locationInNode:self]];
if (currentTouch == nil && [node isEqual:self.testNode2])
{
currentTouch = touch;
}
}
-(void)touchesMoved:(NSSet*) touches withEvent:(UIEvent*) event
{
UITouch *touch = [touches anyObject];
if ([touch isEqual:currentTouch])
{
self.testNode2.position = [touch locationInNode:self];
}
}
-(void)touchesEnded:(NSSet*) touches withEvent:(UIEvent*) event
{
UITouch *touch = [touches anyObject];
if ([touch isEqual:currentTouch])
{
self.testNode2 = nil;
currentTouch = nil;
}
}