getCharactersFromNSCharacterSet.swift

extension NSCharacterSet {
    var characters:[String] {
        var chars = [String]()
        for plane:UInt8 in 0...16 {
            if self.hasMemberInPlane(plane) {
                for (var c:UTF32Char = UInt32(plane) << 16; c < (UInt32(plane) + 1) << 16; c += 1) {
                    if self.longCharacterIsMember(c) {
                        let s = NSString(bytes: &c, length: 4, encoding: NSUTF32LittleEndianStringEncoding)!
                        chars.append(String(s))
                    }
                }
            }
        }
        return chars
    }
}

let charset = NSCharacterSet.URLQueryAllowedCharacterSet()
print(charset.characters.joinWithSeparator(""))