swift convert Range to [Int]

Question

how to convert Range to Array

I tried:

let min = 50
let max = 100
let intArray:[Int] = (min...max)

get error Range<Int> is not convertible to [Int]

I also tried:

let intArray:[Int] = [min...max]

and

let intArray:[Int] = (min...max) as [Int]

they don't work either.

David Skrundz · Accepted Answer · 2018-01-17T16:23:16.493

311

You need to create an Array<Int> using the Range<Int> rather than casting it.

let intArray: [Int] = Array(min...max)

edited Jan 17 '18 at 16:23

answered Aug 19 '15 at 18:51

David Skrundz

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1

thanks, I just figured it while you sent your answer – haitham Aug 19 '15 at 18:52

score 46 · Answer 2 · answered Aug 19 '15 at 18:51

46

Put the Range in the init.

let intArray = [Int](min...max)

answered Aug 19 '15 at 18:51

Mr Beardsley

3,743
22
28

Perfect! Thanks @MrBeardsley – PhillipJacobs Oct 18 '19 at 07:29

haitham · Answer 3 · 2017-09-26T21:52:16.443

18

I figured it out:

let intArray = [Int](min...max)

Giving credit to someone else.

edited Sep 26 '17 at 21:52

answered Aug 19 '15 at 18:51

haitham

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score 15 · Answer 4 · answered Aug 19 '15 at 18:51

15

Use map

let min = 50
let max = 100
let intArray = (min...max).map{$0}

answered Aug 19 '15 at 18:51

vadian

274,689
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adding why it works would be beneficial for people who are reading this kind of questions. For example stating that it creates a CoutableClosedRange which implements Sequence protocol, therefore map is possible and it yields a new int lazily when performing map operation. Some background knowledge is always good – denis631 Dec 05 '17 at 12:15
The other answers are interesting but this one actually answers the question. Big up. – Dan Rosenstark Jan 12 '19 at 21:05

score 15 · Answer 5 · answered Aug 19 '15 at 18:52

15

do:

let intArray = Array(min...max)

This should work because Array has an initializer taking a SequenceType and Range conforms to SequenceType.

answered Aug 19 '15 at 18:52

ad121

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score 4 · Answer 6 · answered Aug 05 '17 at 09:23

4

Interesting that you cannot (at least, with Swift 3 and Xcode 8) use Range<Int> object directly:

let range: Range<Int> = 1...10
let array: [Int] = Array(range)  // Error: "doesn't conform to expected type 'Sequence'"

Therefore, as it was mentioned earlier, you need to manually "unwrap" you range like:

let array: [Int] = Array(range.lowerBound...range.upperBound)

I.e., you can use literal only.

answered Aug 05 '17 at 09:23

devforfu

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The reason for this is because Ranges aren't Collections. The distinction between Range and Countable Range is that the latter can be iterated over by an Integer value. For that reason Countable Range is a collection type in swift but range is not. – Corey Zambonie Nov 15 '17 at 16:04
That's right, and I wasn't expecting this, i.e. two different range classes. Probably due to Pythonic interpretation of `range()`. – devforfu Nov 15 '17 at 16:13

score 3 · Answer 7 · answered Oct 13 '17 at 23:03

3

Since Swift 3/Xcode 8 there is a CountableRange type, which can be handy:

let range: CountableRange<Int> = -10..<10
let array = Array(range)
print(array)
// prints: 
// [-10, -9, -8, -7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

It can be used directly in for-in loops:

for i in range {
    print(i)
}

answered Oct 13 '17 at 23:03

killobatt

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This is (now) the correct way to handle the task. Also works in Swift 4. – Ash Nov 16 '17 at 08:28

score 1 · Answer 8 · answered Feb 28 '19 at 05:00

You can implement ClosedRange & Range instance intervals with reduce() in functions like this.

func sumClosedRange(_ n: ClosedRange<Int>) -> Int {
    return n.reduce(0, +)
}
sumClosedRange(1...10) // 55

func sumRange(_ n: Range<Int>) -> Int {
    return n.reduce(0, +)
}
sumRange(1..<11) // 55

swift convert Range to [Int]

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