Swift - Leave last X number items in array

Question

I have array with 50 items. How to leave in the array only the last 30 items without for loop?

Possible duplicate of [In Swift, what's the cleanest way to get the last two items in an Array?](https://stackoverflow.com/questions/31007643/in-swift-whats-the-cleanest-way-to-get-the-last-two-items-in-an-array) — pckill, Feb 20 '19 at 21:08

score 2 · Accepted Answer · answered Feb 17 '19 at 01:07

2

You can use an ArraySlice:

let lastThirty = array[20...]

Note that lastThirty is of type ArraySlice, so to get it back as an array, you can do:

let lastThirtyArray = Array(lastThirty)

You can read more about ArraySlices here.

answered Feb 17 '19 at 01:07

kbunarjo

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if I have more than 50 items can I use `array[array.count-30...]` ?? – Bogdan Bogdanov Feb 17 '19 at 01:09
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yes you can! You might want to have a check to make sure that your array is longer than 30 before doing the splicing though. – kbunarjo Feb 17 '19 at 01:12

score 0 · Answer 2 · answered Feb 17 '19 at 01:04

0

  let a1 = [1,2,3,4,5]
  print(a1[2...])

so you just need the array[20...]

or array.dropfirst(20)

answered Feb 17 '19 at 01:04

E.Coms

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`dropFirst(_:)` is preferable, because it gracefully handles going out of bounds – Alexander Feb 17 '19 at 04:00
This will return 30 elements only if the array has exactly 50 elements. – Leo Dabus Feb 17 '19 at 05:07

score 0 · Answer 3 · answered Feb 17 '19 at 05:10

What you are looking for is collections method suffix

func suffix(_ maxLength: Int) -> ArraySlice

It will return n elements up to the number of elements in your collection:

let input = Array(1...100)
let last30 = input.suffix(30)  // [71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100]

Swift - Leave last X number items in array

3 Answers3