Split string by two symbols in Swift - swift

Question

I would like to split the string by two symbols in Swift. So after string "df57g5df7g" I would like to obtain an Array ["df","57","g5","df","7g"].
Is it possible to force iterator
for i in word.characters {
print(i)
}
to jump by two symbols, and get acsess to the next symbol inside the loop?

Answer 1

A simple while loop:
let str = "df57g5df7g"
var startIndex = str.startIndex
var result = [String]()
repeat {
let endIndex = startIndex.advancedBy(2, limit: str.endIndex)
result.append(str[startIndex..<endIndex])
startIndex = endIndex
} while startIndex < str.endIndex
print(result)
Or something more Swifty:
let result = 0.stride(to: str.characters.count, by: 2).map { i -> String in
let startIndex = str.startIndex.advancedBy(i)
let endIndex = startIndex.advancedBy(2, limit: str.endIndex)
return str[startIndex..<endIndex]
}

Answer 2

This might not be the slickest solution, but it works:
var word = "df57g5df7g"
var pairsArray = [String]()
while word.characters.count > 1 {
let firstCharacter = word.removeAtIndex(word.startIndex)
let secondCharacter = word.removeAtIndex(word.startIndex)
pairsArray.append("\(firstCharacter)\(secondCharacter)")
}
print(pairsArray)
The result is:
["df", "57", "g5", "df", "7g"]

Answer 3

This is the best solution I've seen, taken from the SwiftSequence library.
extension CollectionType {
public func chunk(n: Index.Distance) -> [SubSequence] {
var res: [SubSequence] = []
var i = startIndex
var j: Index
while i != endIndex {
j = i.advancedBy(n, limit: endIndex)
res.append(self[i..<j])
i = j
}
return res
}
}
let word = "df57g5df7g"
let pairs = word.characters.chunk(2).map(String.init)
print(pairs) //["df", "57", "g5", "df", "7g"]
You can see it in action here.