In Swift, what's the cleanest way to get the last two items in an Array?

Question

Is there a cleaner way to get the last two items of an array in Swift? In general, I try to avoid this approach since it\'s so easy to be off-by-one with the indexes. (Using

Answer 1

myList[-2:]

Yes, I have an enhancement request filed asking for negative index notation, and I suggest you file one too.

However, you shouldn't make this harder on yourself than you have to. The built-in global suffix function does exactly what you're after:

let oneArray = ["uno"]
let twoArray = ["uno", "dos"]
let threeArray = ["uno", "dos", "tres"]

let arr1 = suffix(oneArray,2) // ["uno"]
let arr2 = suffix(twoArray,2) // ["uno", "dos"]
let arr3 = suffix(threeArray,2) // ["dos", "tres"]

The result is a slice, but you can coerce it to an Array if you need to.

Answer 2

More generic answer ...

let a1 = [1,2,3,4,5]
let a2 = ["1","2","3","4","5"]

func getLast<T>(array: [T], count: Int) -> [T] {
  if count >= array.count {
    return array
  }
  let first = array.count - count
  return Array(array[first..<first+count])
}

getLast(a1, count: 2) // [4, 5]
getLast(a2, count: 3) // ["3", "4", "5"]

Answer 3

I doubt it's going to make you that much happier, but the math is certainly simpler:

func getLastTwo(array: [String]) -> [String] {
    if array.count <= 1 {
        return array
    } else {
        return array.reverse()[0...1].reverse()
    }
}

Note that reverse() is lazy, so this isn't particularly expensive.