How to create Swift empty two dimensional array with size

Question

I try to do smth like this:

let myArray: [[MyClass]] = [5,5]

where [5,5] is size of array. I can\'t do this.

Answer 1

If you want to make a multidimensional array of value types (i.e. Ints, Strings, structs), the syntax in codester's answer works great:

Swift 4

var arr = [[Int]](repeating: [Int](repeating: 0, count: 5), count: 5)

Swift Earlier

var arr = [[Int]](count: 5, repeatedValue: [Int](count: 5, repeatedValue: 0))
arr[0][1] = 1
// arr is [[0, 1, 0, 0, 0], ...

If you make a multidimensional array of reference types (i.e. classes), this gets you an array of many references to the same object:

class C {
    var v: Int = 0
}
var cArr = [[C]](count: 5, repeatedValue: [C](count: 5, repeatedValue: C()))
// cArr is [[{v 0}, {v 0}, {v 0}, {v 0}, {v 0}], ...
cArr[0][1].v = 1
// cArr is [[{v 1}, {v 1}, {v 1}, {v 1}, {v 1}], ...

If you want to make an array (uni- or multidimensional) of reference types, you might be better off either making the array dynamically:

var cArr = [[C]]()
for _ in 0..<5 {
    var tmp = [C]()
    for _ in 0..<5 {
        tmp += C()
    }
    cArr += tmp
}
// cArr is [[{v 0}, {v 0}, {v 0}, {v 0}, {v 0}], ...
cArr[0][1].v = 1
// cArr is [[{v 0}, {v 1}, {v 0}, {v 0}, {v 0}], ...

(See slazyk's answer for equivalent shorter syntax using map().)

Or making an array of optionals and filling in their values:

var optArr = [[C?]](count: 5, repeatedValue: [C?](count: 5, repeatedValue: nil))
// optArr is [[nil, nil, nil, nil, nil], ...
optArr[0][1] = C()
// optArr is [[nil, {v 0}, nil, nil, nil], ...