Moving objects in an array using UITouch SpriteKit - nsmutablearray

Question

I'm trying to move SKSpritenode in an array like a scrollbar where all objects move together according to the move location:
- (void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch * touch = [touches anyObject];
CGPoint location = [touch locationInNode:self];
NSEnumerator *e = [_blockStream objectEnumerator];
PBAIceBlock *block;
while (block = [e nextObject])
{
//this says the expresion is not assignable
block.position.y += location.y;
}
}
Where the comments says, I get an error, could some one please point me in the right direction on how to implement something like this?
Using Sprite kit in xcode 5?

Answer 1

A solution is to create a CGPoint to store a value. set that value in touchesBegan, then:
- (void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch * touch = [touches anyObject];
CGPoint location = [touch locationInNode:self];
int yOFFSET = location.y - _touchLocation.y ;
NSLog(#"yOFFSET : %d", yOFFSET);
NSEnumerator *e = [_blockStream objectEnumerator];
PBAIceBlock *block;
while (block = [e nextObject]) {
CGPoint _center = block.position;
_center.y += yOFFSET;
block.position = _center;
}
_touchLocation = location;
}
This problem happened because you cannot call the position.y specifically.