Snake game movement issue Spritekit - ios

Question

I am trying to create a basic snake game using Swift and Spritekit. I have a sprite moving on the screen and when i swipe it starts moving in the swipe direction. I do this in the update method where I change the position of the sprite based on the swipe direction, a set speed and a fixed duration.
e.g. direction.x * blockMovePerSecond * CGFloat(actionDuration)
I have the sprites following each other, however, as soon as i swipe and the first sprite changes direction, the one following it moves diagonally instead of first on the x-axis and then the y-axis like a normal snakes game.
I tried the following options:
Tried keeping the distance that the sprite moves on each update equal
to the distance between the two sprites. However, the sprite runs off
the screen when i do that.
Made the first sprite create a path for the rest of the sprites to follow. However, the second sprite
runs off the screen and never shows up again. I think the problem is
because the path is open.
Here's my move method code for the sprites following the first sprite (snake head):
{
var temp:NSValue = lastNodeLocation // the lastnodelocation is from first sprite location
var tempNodeDirection = lastNodeDirection
let actionDuration = 1.0
let distanceToMoveThisFrame = tempNodeDirection.CGPointValue() * blockMovePerSecond * CGFloat(actionDuration)
var currentPosition = NSValue(CGPoint: blocksOfAlphabets[i].position)
let beforeDistance = CGPoint(x: temp.CGPointValue().x - currentPosition.CGPointValue().x, y: temp.CGPointValue().y - currentPosition.CGPointValue().y)
lastNodeLocation = NSValue(CGPoint: blocksOfAlphabets[i].position)
// move node to new location
var moveAction = SKAction.moveTo(temp.CGPointValue(), duration: 1.0)
node.runAction(moveAction)
}
Can somebody please help?
Thanks
Shuchi

Answer 1

Well your problem is that the runAction-methods don't wait to complete. So if you call another runAction-method while a sprite is already running an action, the new action will be started immediately.
You can work with sequences to finish the x-axis first: SKAction:sequence

Answer 2

I think the easiest thing to do here is to keep an array of snake sprite components (let's call these sprites a "Rib").
Every 5 seconds add a new Rib to the end of the array to make the snake grow.
Then, each half second in the update() method (or however long you want it to be):
check for any swipes that have happened since the last update and change direction of the first rib (the snake head) in the direction of the swipe.
now run through the snake array in reverse and set the location of node (n) to the node position of node (n-1).
There are other ways you could do it but I think this would be the easiest.