Split String in Swift by their capital letters

Question

I want to split an simple String by their capital letters into an array. It should look something like this:

let teststring = "NaCuHHe"

and the result should be:

["Na", "Cu", "H", "He"]

I tried the following:

func capitalLetters(s: String) -> [Character] {
    return s.characters.filter { ("A"..."Z").contains($0) }
}

I searched trough the documentation and other websites but i did not find any helpful things. Im at the end. I don't know what to do more hence im really new to swift. It still gives me only the capital ones and i don't know how to change that it gives me the things behind de capital one as well.

Answer 1

Using Regex -

func splitYourString(_ s: String) ->[String] {
let regex = try! NSRegularExpression(pattern: "([a-z]*)([A-Z])") //<-Use capturing, `([a-z]*)`->$1, `([A-Z])`->$2
return regex.stringByReplacingMatches(in: s, range: NSRange(0..<s.utf16.count),
                                      withTemplate: "$1 $2").trimmingCharacters(in: .whitespacesAndNewlines) .components(separatedBy: " ")
}
print(splitYourString("NaCuHHe"))     //["Na", "Cu", "H", "He"]

Answer 2

A bit late to the party, but here's a straightforward Swift 3 approach using whitespace-delimiting. Might not be as elegant as the functional or iterator approaches, but it doesn't involve making any custom extensions on existing classes.

    let originalString = "NaCuHHe"
    var newStringArray: [String] = []
    for character in originalString.characters {
        if String(character) == String(character).uppercased() {
            newStringArray.append(" ")
        }
        newStringArray.append(String(character))
    }

    let newString = newStringArray.joined().trimmingCharacters(in: .whitespacesAndNewlines).components(separatedBy: " ")
    print(newString) // Returns ["Na", "Cu", "H", "He"]