Sum of digits of each elements inside an array of integers (Swift)

Question

In swift 3, how to calculate each integers digits summation inside an array?

Example:

var nums = [111,222,333] 

The output should be like this: [3,6,9]

which is the result of calculating: [1+1+1, 2+2+2, 3+3+3]

Answer 1

You could implement it as follows:

let nums = [111,222,333]

func transform(_ element: Int) -> Int {
    var intsChars: [Int] = []
    for char in "\(element)".characters {
        intsChars.append(Int(String(char))!)
    }

    return intsChars.reduce(0, +)
}

let result = nums.map { transform($0) }

print(result) // [3, 6, 9]

UPDATE:

As mentioned in Martin R's answer :

func digitSum(_ n : Int) -> Int {
    var n = n
    var sum = 0
    while n > 0 {
        sum += n % 10 // Add least significant digit ...
        n /= 10   // ... and remove it from the number.
    }
    return sum
}

you could also achieve the same output:

let result = nums.map { digitSum($0) } // [3, 6, 9]