What's the best way to cut Swift string into 2-letter-strings?

Question

I need to split a string into 2-letter pieces. Like “friend\" -> \"fr\" \"ie\" \"nd\". (Okay, its a step for me to change HEX string to Uint8 Array)

My code is

Answer 1

Another option just for fun:

extension String {
    var pairs:[String] {
        var result:[String] = []
        let chars = Array(characters)
        for index in 0.stride(to: chars.count, by: 2) {
            result.append(String(chars[index..