Swift – Given an Int like 30 how to take ranged numbers by 7?

Let’s suppose I have an Int like 30, how can i take ranged numbers by 7 and put them into a list of pairs in Swift?

For example in this case it would be [(1, 7), (8, 14), (15, 21), (22, 28), (29, 30)] where the last couple is 29-30.

I found a code in Kotlin that may do that but I don’t know how could it be in Swift since I don’t know Kotlin. I post it in case it is helpful.

val myInt = 28
val list = (1..ceil(myInt/7.0).toInt()).mapIndexed { index, i ->
    7*index + 1 to (7*index + 7).coerceAtMost(myInt)
}

print(list)

Update:

I tried this code so far:

var days = 30
var daysInt: [Int] = []
var index = 0
      
        for i in 1...days {
                
                 if index <= days {
                    if i == 1 {
                        index += 1
                        daysInt.append(index)
                        index += 6
                        daysInt.append(index)
                    } else {
                        index += 1
                        daysInt.append(index)
                        index += 6
                        daysInt.append(index)
                    }
                }
            }

And the output is:

• 0 : 1
  • 1 : 7
  • 2 : 8
  • 3 : 14
  • 4 : 15
  • 5 : 21
  • 6 : 22
  • 7 : 28
  • 8 : 29
  • 9 : 35

All fine but the 35 should be 30.

I’m sure there is a better way.

>Solution :

The Kotlin code

(1..myInt step 7).map { it to min(it + 6, myInt) }

which was suggested in a comment can almost literally be translated to Swift.

With stride() you can create the sequence 1, 8, 15, …, 29, and with map() you can map each value to a tuple:

let days = 30
let list = stride(from: 1, to: days, by: 7).map { ($0, min($0+6, days)) }
print(list)
// [(1, 7), (8, 14), (15, 21), (22, 28), (29, 30)]