What is the syntax for multidimensional array in Swift?

Question

CO fans: before you jump into conclusion it is a duplicate, there are 2 distinct flavours of arrays, and it seems I am asking about less popular one.

So far, I

Answer 1

An example implementation supporting arbitrary number of dimensions:

struct ArrayMultiDimension {
    private var _base:[T]
    let _dimensions: [Int]

    init(initialValue: T, dimensions:Int...) {
        _base = Array(count: reduce(dimensions, 1, *), repeatedValue: initialValue)
        _dimensions =  dimensions
    }
    private func _position2idx(position:[Int]) -> Int {
        assert(position.count == _dimensions.count)
        return reduce(Zip2(_dimensions, position), 0) {
            assert($1.0 > $1.1)
            return $0 * $1.0 + $1.1
        }
    }
    subscript(position:Int...) -> T {
        get { return _base[_position2idx(position)] }
        set { _base[_position2idx(position)] = newValue }
    }
}

// Usage:

var array3d = ArrayMultiDimension(initialValue: "", dimensions: 4,3,2)

for x in 0 ..< 4 {
    for y in 0 ..< 3 {
        for z in 0 ..< 2 {
            array3d[x,y,z] = "\(x)-\(y)-\(z)"
        }
    }
}

array3d[1,2,0] = "foo"

But, this could be very slow...