Swift 3：如何比较二维数组？

Question

我有一个常数stringGrid：

let stringGrid = "08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08 " +
                 "49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00 " +
                 "81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65 " +
                 "52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91 " +
                 "22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80 " +
                 "24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50 " +
                 "32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70 " +
                 "67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21 " +
                 "24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72 " +
                 "21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95 " +
                 "78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92 " +
                 "16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57 " +
                 "86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58 " +
                 "19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40 " +
                 "04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66 " +
                 "88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69 " +
                 "04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36 " +
                 "20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16 " +
                 "20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54 " +
                 "01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48 "

我需要将stringGrid转换为类型为[[Int]]的二维数组。 好的，我尝试使用属性Matrix和实例方法matrix实现结构getMatrixFrom(_:withSize:)，其中withSize是子数组的长度：

struct Matrix {
    var matrix: [[Int]]?

    mutating func getMatrixFrom(_ string: String, withSize size: Int) {

        // foreach two digits inside input.
        var twoDigits: [Int] = []

        // foreach 'size' numbers inside input.
        var list: [Int]?

        // for detecting space symbol inside input.
        var countOfSpaces = 0
        let space: Character = " "

        for symbol in string.characters {

            if symbol == space {
                countOfSpaces += 1
            }

            if countOfSpaces % size == 0 {
                if let subArray = list { self.matrix?.append(subArray) }
                list?.removeAll()
            }

            if twoDigits.count == 2 {
                for digit in twoDigits {
                    list?.append(digit)
                }
                twoDigits.removeAll()
            } else {
                if let digit = Int(String(symbol)) {
                    twoDigits.append(digit)
                } else {
                    print("There is incorrect string for converting! ")
                    return
                }
            }

        }

        print("Done it! ")
    }

}

接下来，我需要检查我的函数getMatrixFrom(_:withSize:)是否有效。我写了一个小单元测试：

import XCTest
@testable import P11

class ConvertingTests: XCTestCase {

    func testConvertingFunction() {
        let input = "08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08 "
        let expected = [[8, 2, 22, 97, 38, 15, 0, 4, 0, 75, 4, 5, 7, 78, 52, 12, 50, 77, 91, 8]]

        var a: Matrix = Matrix()

        if let output = a.getMatrixFrom(input, withSize: 20) {
            XCTAssert(output == expected)
        }
    }

}

当然，我的编纂者骂我，因为：

  

二元运算符＆＃39; ==＆＃39;不能适用于两个[[Int]]＆＃39;操作数。

嗯，我同意了。我决定对现有结构Matrix实施扩展：

extension Matrix: Equatable {
    static func == (lhs: Matrix, rhs: Matrix) -> Bool {
        if let l = lhs.matrix, let r = rhs.matrix {
            return l == r
        }
    }
}

然而，构建时错误并没有消失。 ：

使用Swift 3比较二维数组的好方法是什么？