Following a path in Spritekit EXC_BAD_ACCESS - swift

Question

I have a simple Snake game where the head draws a UIBezier path. That part works fine:
func addLineToSnakePath(snakeHead: SnakeBodyUnit) {
//add a new CGPoint to array
activeSnakePathPoints.append(CGPoint(x: snakeHead.partX, y: snakeHead.partY))
let index = activeSnakePathPoints.count-1
if (index == 1) {
path.moveToPoint(activeSnakePathPoints[index-1])
}
path.addLineToPoint(activeSnakePathPoints[index])
shapeNode.path = path.CGPath
}
The path generates with swipes as the Head moves around the screen. Now I add a body unit to follow the UIBezier path and I get a bad access error.
func addBodyPart() {
let followBody = SKAction.followPath(path.CGPath, asOffset: true, orientToPath: false, duration: 1.0)
snakePart.runAction(followBody)
}
Crash at:
0 SKCFollowPath::cpp_willStartWithTargetAtTime(SKCNode*, double)
Thread 1 EXC_BAD_ACCESS

Answer 1

Looking at the code I would rather strengthen my code this way:
func addLineToSnakePath(snakeHead: CGPoint) {
let count = activeSnakePathPoints.count
if count == 0 { return } // The snake don't have an head..
//add a new CGPoint to array
activeSnakePathPoints.append(CGPoint(x: snakeHead.x, y: snakeHead.y))
guard count > 1 else {
// There are only two element (the head point and the new point) so:
path = UIBezierPath.init()
path.moveToPoint(activeSnakePathPoints[count-1])
shapeNode.path = path.CGPath
return
}
// There are some elements:
path.addLineToPoint(activeSnakePathPoints[count-1])
shapeNode.path = path.CGPath
}
Next, when you make the followPath action I've seen you use offset value to true ( I don't know if this is wanted from you..):
asOffset : If YES, the points in the path are relative offsets to the
node’s starting position. If NO, the points in the node are absolute
coordinate values.
In other words true means the path is relative from the sprite's starting position, false means absolute
Finally in the line:
snakePart.runAction(followBody)
I don't know what is snakePart but you use shapeNode in your function
Update:
Thinking about your crash, seems snakePart is not a valid SKNode (like when you try to use a sprite or shape without initialize itself)