emoji - Swift `join` hangs when joining string with country flag -

i discovered while working in swift 1.2. have reported bug. wonder why?

import uikit  var str = "🇬🇧 lhr ✈️ sfo 🇺🇸"  ([str] nsarray).componentsjoinedbystring("") // work join("", [str]) // hangs forever 

apple has fix problem in swift 2.0, join replace method joinwithseparator(separator: string) -> string works fine flags.

here code snippet.

var str = "🇬🇧 lhr ✈️ sfo 🇺🇸"  ([str] nsarray).componentsjoinedbystring("") // work  [str].joinwithseparator("") 

output

🇬🇧 lhr ✈️ sfo 🇺🇸 🇬🇧 lhr ✈️ sfo 🇺🇸 🇬🇧 lhr ✈️ sfo 🇺🇸