Reorder string characters in Swift

Question

So, let's say I have a String that is: "abc" and I want to change each character position so that I can have "cab" and later "bca". I want the character at index 0 to move to 1, the one on index 1 to move to 2 and the one in index 2 to 0.

What do I have in Swift to do this? Also, let's say instead of letters I had numbers. Is there any easier way to do it with integers?

Answer 1

Swift 2:

extension RangeReplaceableCollectionType where Index : BidirectionalIndexType {
  mutating func cycleAround() {
    insert(removeLast(&self), atIndex: startIndex)
  }
}

var ar = [1, 2, 3, 4]

ar.cycleAround() // [4, 1, 2, 3]

var letts = "abc".characters
letts.cycleAround()
String(letts) // "cab"

Swift 1:

func cycleAround<C : RangeReplaceableCollectionType where C.Index : BidirectionalIndexType>(inout col: C) {
  col.insert(removeLast(&col), atIndex: col.startIndex)
}

var word = "abc"

cycleAround(&word) // "cab"