Swift setting a struct value within another struct init - swift

Question

I have Cell struct values (position:, state:) which need to be set within the init of my Grid struct, but I can't seem to set these values of Cell.
struct Cell {
var position: (Int,Int)
var state: CellState
init(_ position: (Int,Int), _ state: CellState) {
self.position = (0,0)
self.state = .empty
}
}
func positions(rows: Int, cols: Int) -> [Position] {
return (0 ..< rows)
.map { zip( [Int](repeating: $0, count: cols) , 0 ..< cols ) }
.flatMap { $0 }
.map { Position(row: $0.0,col: $0.1) }
}
I've commented all of the ways that I've tried to set the position to (row, col)
struct Grid {
static let offsets: [Position] = [
(row: -1, col: 1), (row: 0, col: 1), (row: 1, col: 1),
(row: -1, col: 0), (row: 1, col: 0),
(row: -1, col: -1), (row: 0, col: -1), (row: 1, col: -1)
]
var rows: Int = 10
var cols: Int = 10
var cells: [[Cell]] = [[Cell]]()
init(_ rows: Int,
_ cols: Int,
cellInitializer: (Int, Int) -> CellState = { _,_ in .empty } ) {
self.rows
self.cols
self.cells = [[Cell]](repeatElement([Cell](repeatElement(Cell((0,0), .empty), count: cols)),count: rows))
positions(rows: rows, cols: cols).forEach { row, col in
// var position = cells(position: (row, col)) => cannot call value of non-function type '[[Cell]]'
// cells.position = (row, col) => value type of '[[Cell]] has no member position'
// cells.position(row, col) => value type of '[[Cell]] has no member position'
// position *= cells.position(row, col) => closure cannot implicitly capture a mutating self parameter
}
}
}
Clearly the Cell struct has a property of position, so why can't I access it?

Answer 1

The problem is that none of your lines are actually accessing instances of your Cell struct.
Here's a functioning adaptation of your code. I allowed myself to remove extra stuff that seem to have been left out from your codebase:
struct Cell {
var position: (Int,Int)
init(_ position: (Int,Int)) {
self.position = (0,0)
}
}
func positions(rows: Int, cols: Int) -> [(Int, Int)] {
return (0 ..< rows)
.map { zip( [Int](repeating: $0, count: cols) , 0 ..< cols ) }
.flatMap { $0 }
.map { ($0.0, $0.1) }
}
struct Grid {
var rows: Int = 10
var cols: Int = 10
var cells: [[Cell]] = [[Cell]]()
init(_ rows: Int, _ cols: Int) {
self.rows = rows
self.cols = cols
self.cells = Array.init(repeating: Array.init(repeating: Cell((0,0)), count: cols), count: cols)
positions(rows: rows, cols: cols).forEach { row, col in
cells[row][col].position = (row, col)
}
}
}
let g = Grid(1, 2)
print(g.cells[0][1].position)
Now, for a more detailed explanation of the errors you encountered:
var position = cells(position: (row, col))
Here you're not setting anything on any cell. Instead, you're trying to call your grid as if it was a function, with a parameter position: (Int, Int).
cells.position = (row, col)
Here you're trying to set a property position on your matrix ([[Cell]]). And obviously, Swift complains that such property does not exists in its builtin type Array.
cells.position(row, col)
Here you're trying to set a property position on your matrix ([[Cell]]) and call it as a function with two parameters Int. The problem is similar as above.
position *= cells.position(row, col)
Here I'm can't tell what's going on, since position does not seems to have been declared in your code. I guess it comes from elsewhere in your codebase, or maybe it's merely a typo.

Answer 2

The issue here is that you are trying to access cells.position but cells is a two-dimensional array.
cells.position = (row, col) => value type of '[[Cell]] has no member position'
You could loop through the cells and set the position of each one.
So in your forEach loop you could write instead
cells[row][column].position = (row, col)
and that should do it.