Force the SKAction.move to be completed - swift - swift

Question

I'm creating a Snake Game using swift and the library SpriteKit.
To control the direction of the snake, the user has to swipe on the screen. To check which was the direction of the swipe, I use UISwipeGestureRecognizer .
Now, I have to pass the information (direction of the swipe) from the GameViewController.swift file to the GameScene.swift file. To to that, I declare a 4 items array called movesConoller:
movesController[false, false, false, false]
If the user swipes up, the first element of the array turns true, if he scrolls down, the second element turns true and the first one false... etc. etc.
Now, in the GameScene.swift file I have to say what the Snake has to do if the player moves up.
For this reason, I use 2 more variables:
var playerX:CGFloat = 0
var playerY:CGFloat = 0
and then I created this code
if movesController[0] == true {
playerY += 56
}
if movesController[1] == true {
playerY -= 56
}
if movesController[2] == true {
playerX += 56
}
if movesController[3] == true {
playerX -= 56
}
Now I create the movement
let startPoint = CGPoint(x: player.position.x, y: player.position.y )
let endPoint = CGPoint(x: playerX + player.position.x, y: playerY + player.position.y)
let moveIt = SKAction.move(to: endPoint, duration:0.1)
player.run(moveIt)
So, every time the program is executed, the playerX and playerYvariables become equal to 0. Then, based on the direction of the swipe, they are added or subtracted 56.
To move the snake I just say to the head to move from his startPointto his endPoint in 0.1 seconds.
Another thing I added is the tail. To create it I use two arrays, snakeX and snakeY.
To these two empty arrays (of type CGFloat) I add the previous position of the snake and then, if the score remains the same, the last element of each array is deleted. Else, the last element isn't deleted and remains in his array.
Whit this method, I make the tail growing when the snake eats an apple.
BUT the head moves 56 in 0.1seconds. This means that he makes a movement of 8 pixels at each execution. Because of that, I have to add to snakeX and snakeY the X and Y values every 7 execution of the program.
This is the problem. If the player swipes on the screen just after 7 execution of the program, the movement of the tail will be perfect. But if the player swipes before the 7 execution, there will be a problem. Let's suppose the snake is moving right and the player swipes up when the program is at its 4th execution.
//snakeX and snakeY values before the swipe
snakeX[168, 112, 56, 0] //all this numbers are multiple of 56
snakeY[224, 224, 224, 224] //the snake is moving right, the Y value doesn't change.
//snakeX and snakeY values after the swipe
snakeX[168 ,112 ,56 , 0]
snakeY[248, 224, 224, 224] //look at the first element
248 is not a multiple of 56. The snake moved Up at the 4th execution, after 3 execution his position will be added to the arrays. But in 3 execution he had moved of 24pixel.
Because of that, I'll get this bug
as you can see, the tail doesn't make a perfect corner.
The snake head doesn't complete his movement of 56 pixels. When I swipe, it leaves his movement and starts another one. Is there a way I can tell the head to always complete his movement before doing another one?

Answer 1

You're sort of trying to use a pixel-based approach to what's basically a grid-based game, but maybe something like this will work...
Make a variable controlling whether movement is allowed:
var moveAllowed = true
Guard your movement code with that variable:
if moveAllowed {
if movesController[0] == true {
playerY += 56
}
...
}
When you schedule the movement action, toggle moveAllowed, and add a completion handler to toggle it back after the action finishes:
...
moveAllowed = false
let moveIt = SKAction.move(to: endPoint, duration:0.1)
player.run(moveIt) { self.moveAllowed = true }
(The self.moveAllowed might be just moveAllowed depending on how you have things structured, but I can't tell from your fragments.)
Edit: I just realized that maybe you're setting snakeX and snakeY based on player.position. It's not really clear. In any case, then you'd use the same idea but copying from player.position only when moveAllowed is true. Basically that variable is telling you if the action is still running or not.