الفهرسة المخصّصة (Subscripts)

struct Grid {
    var values = Array(repeating: 0, count: 9)   // شبكة 3×3

    subscript(row: Int, column: Int) -> Int {
        get {
            return values[row * 3 + column]
        }
        set(newValue) {
            values[row * 3 + column] = newValue
        }
    }
}

var grid = Grid()
grid[0, 1] = 5
print(grid[0, 1])   // 5

struct Squares {
    subscript(n: Int) -> Int {
        return n * n
    }
}

let squares = Squares()
print(squares[4])   // 16

struct Matrix {
    subscript(row: Int, col: Int) -> Double { /* ... */ 0 }
    subscript(index: String) -> Double { /* ... */ 0 }
}

enum Planet: Int {
    case mercury = 1, venus, earth, mars

    static subscript(n: Int) -> Planet {
        return Planet(rawValue: n)!
    }
}

let earth = Planet[3]   // يُستدعى على النوع Planet مباشرة