Array2D.swift

class Array2D<T> {
    let columns: Int
    let rows: Int
    var array: Array<T?>
    
    init(columns: Int, rows: Int) {
        self.columns = columns
        self.rows = rows
        array = Array<T?>(count: rows * columns, repeatedValue: nil)
    }
    
    subscript(column: Int, row: Int) -> T? {
        get {
            return array[(row * columns) + column]
        }
        set(newValue) {
            array[(row * columns) + column] = newValue
        }
    }
    
}

var array2D = Array2D<String>(columns: 3, rows: 3)
array2D[1, 1] = "a"
array2D[1, 1]