find-sum-of-digits()

Step 1: Understand the Task

Our task is to create a function in Swift which will find the sum of digits of a given number.

Let's consider an example number, 123. The sum of its digits would be 1 + 2 + 3 = 6.

We will achieve this task by repeatedly dividing the number by 10 and adding the rightmost digit to our sum until the number becomes 0.

swift
let number = 123
var sum = 0

Step 2: Begin the Loop

Let's start a while loop which continues until the number is not zero.

We don't know beforehand how many digits the number will have, hence a while loop is a good choice for such scenarios.

swift
while number > 0 {
  // Calculate the sum of digits
}

Step 3: Extract Rightmost Digit and Add to Sum

Inside the loop, we will calculate the rightmost digit of the number using the modulo operation. We then add this digit to our sum.

swift
while number > 0 {
  let digit = number % 10
  sum += digit
}

Step 4: Remove Rightmost Digit

To remove the rightmost digit from the number, we will divide the number by 10.

swift
while number > 0 {
  let digit = number % 10
  sum += digit
  number /= 10
}

Conclusion

The Swift code implementation of our function to find the sum of digits for a given number is as follow:

swift
var number = 123
var sum = 0
while number > 0 {
  let digit = number % 10
  sum += digit
  number /= 10
}
print(sum) \ The output will be 6

In the end, the variable sum holds the sum of all the digits of the original number.