Draw a grid with SpriteKit - ios

Question

What would be the best way to draw a grid like this by using the SpriteKit 2D game engine?
Requirements:
Input programatically the number of columns and rows (5x5, 10x3, 3x4 etc.).
Draw it programmatically using something like SKSpriteNode or SKShapeNode, since just using images of a square like this doesn't seem very efficient to me.
The squares should have a fixed size (let's say each is 40x40).
The grid should be vertically and horizontally centred in the view.
I'm planning to use a SKSpriteNode (from an image) as a player moving in different squares in this grid.
So, I'll save in a 2 dimensional array the central point (x,y) of each square and then move from the player's current position to that position. If you have a better suggestion for this too, I'd like to hear it.
I would appreciate a solution in Swift (preferably 2.1), but Objective-C would do too. Planning on using this only on iPhone devices.
My question is close to this one. Any help is appreciated.

Answer 1

I suggest you implement the grid as a texture of an SKSpriteNode because Sprite Kit will renders the grid in a single draw call. Here's a example of how to do that:
class Grid:SKSpriteNode {
var rows:Int!
var cols:Int!
var blockSize:CGFloat!
convenience init?(blockSize:CGFloat,rows:Int,cols:Int) {
guard let texture = Grid.gridTexture(blockSize: blockSize,rows: rows, cols:cols) else {
return nil
}
self.init(texture: texture, color:SKColor.clear, size: texture.size())
self.blockSize = blockSize
self.rows = rows
self.cols = cols
}
class func gridTexture(blockSize:CGFloat,rows:Int,cols:Int) -> SKTexture? {
// Add 1 to the height and width to ensure the borders are within the sprite
let size = CGSize(width: CGFloat(cols)*blockSize+1.0, height: CGFloat(rows)*blockSize+1.0)
UIGraphicsBeginImageContext(size)
guard let context = UIGraphicsGetCurrentContext() else {
return nil
}
let bezierPath = UIBezierPath()
let offset:CGFloat = 0.5
// Draw vertical lines
for i in 0...cols {
let x = CGFloat(i)*blockSize + offset
bezierPath.move(to: CGPoint(x: x, y: 0))
bezierPath.addLine(to: CGPoint(x: x, y: size.height))
}
// Draw horizontal lines
for i in 0...rows {
let y = CGFloat(i)*blockSize + offset
bezierPath.move(to: CGPoint(x: 0, y: y))
bezierPath.addLine(to: CGPoint(x: size.width, y: y))
}
SKColor.white.setStroke()
bezierPath.lineWidth = 1.0
bezierPath.stroke()
context.addPath(bezierPath.cgPath)
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return SKTexture(image: image!)
}
func gridPosition(row:Int, col:Int) -> CGPoint {
let offset = blockSize / 2.0 + 0.5
let x = CGFloat(col) * blockSize - (blockSize * CGFloat(cols)) / 2.0 + offset
let y = CGFloat(rows - row - 1) * blockSize - (blockSize * CGFloat(rows)) / 2.0 + offset
return CGPoint(x:x, y:y)
}
}
And here's how to create a grid and add a game piece to the grid
class GameScene: SKScene {
override func didMove(to: SKView) {
if let grid = Grid(blockSize: 40.0, rows:5, cols:5) {
grid.position = CGPoint (x:frame.midX, y:frame.midY)
addChild(grid)
let gamePiece = SKSpriteNode(imageNamed: "Spaceship")
gamePiece.setScale(0.0625)
gamePiece.position = grid.gridPosition(row: 1, col: 0)
grid.addChild(gamePiece)
}
}
}
Update:
To determine which grid square was touched, add this to init
self.isUserInteractionEnabled = true
and this to the Grid class:
override func touchesBegan(_ touches: Set<UITouch>, withEvent event: UIEvent?) {
for touch in touches {
let position = touch.location(in:self)
let node = atPoint(position)
if node != self {
let action = SKAction.rotate(by:CGFloat.pi*2, duration: 1)
node.run(action)
}
else {
let x = size.width / 2 + position.x
let y = size.height / 2 - position.y
let row = Int(floor(x / blockSize))
let col = Int(floor(y / blockSize))
print("\(row) \(col)")
}
}
}