Get grid location from click in Swift with Spritekit - ios

Question

I have a dynamically generated grid that can give me the location of the center of ones its tiles given the row and column with my gridPosition function, but I can't figure out the opposite. I am trying to keep everything dynamic so this will work on all screens and devices.
How do I get the row and column from the location? I tried reversing how I get the gridPosition but it is off by a lot. Is there an easier way to do this? or did I make an error?
import SpriteKit
import Foundation
class Grid:SKSpriteNode {
var rows:Int!
var cols:Int!
var tileIsValid:[[Bool]]!
var blockSize:CGFloat!
convenience init(blockSize:CGFloat,rows:Int,cols:Int) {
let texture = Grid.gridTexture(blockSize,rows: rows, cols:cols)
self.init(texture: texture, color:SKColor.clearColor(), size: texture.size())
self.blockSize = blockSize
self.rows = rows
self.cols = cols
self.tileIsValid = Array.init(count: rows, repeatedValue: Array.init(count: cols, repeatedValue: false))
}
override init(texture: SKTexture!, color: SKColor, size: CGSize) {
super.init(texture: texture, color: color, size: size)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
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)
let context = UIGraphicsGetCurrentContext()
let bezierPath = UIBezierPath()
let offset:CGFloat = 0.5
// Draw vertical lines
for i in 0...cols {
let x = CGFloat(i)*blockSize + offset
bezierPath.moveToPoint(CGPoint(x: x, y: 0))
bezierPath.addLineToPoint(CGPoint(x: x, y: size.height))
}
// Draw horizontal lines
for i in 0...rows {
let y = CGFloat(i)*blockSize + offset
bezierPath.moveToPoint(CGPoint(x: 0, y: y))
bezierPath.addLineToPoint(CGPoint(x: size.width, y: y))
}
SKColor.blackColor().setStroke()
bezierPath.lineWidth = 1.0
bezierPath.stroke()
CGContextAddPath(context, bezierPath.CGPath)
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return SKTexture(image: image)
}
// give row, col and get cgpoint of tile
func gridPosition(row:Int, col:Int) -> CGPoint {
let offset = blockSize / 2.0 + 0.5
let colsMiddle = (blockSize * (CGFloat(cols)) / 2.0)
let tileWidth = (CGFloat(col) * blockSize)
let x = tileWidth - colsMiddle + offset
let rowsMiddle = ((blockSize * CGFloat(rows)) / 2.0)
let gridHeightNum = CGFloat(rows - row - 1)
let gridHeight = (gridHeightNum * blockSize)
let y = gridHeight - rowsMiddle + offset
return CGPoint(x:x, y:y)
}
func gridIsValid(location: CGPoint) -> Bool {
let offset = blockSize / 2.0 + 0.5
let colsMiddle = (blockSize * (CGFloat(cols)) / 2.0)
let midColCalc = location.x + colsMiddle - offset
let midColCalc2 = midColCalc / blockSize
let col = Int(round(abs(midColCalc2)))
let rowsMiddle = ((blockSize * CGFloat(rows)) / 2.0)
let midRowCalc = location.y + rowsMiddle - offset
let midRowCalc2 = midRowCalc / blockSize
let midRowCalc3 = midRowCalc2 + 1 + CGFloat(rows)
let row = Int(round(abs(midRowCalc3)))
print ("\(col) \(row)")
return self.tileIsValid[col][row]
}