let bytes = [84,11]

// Imperative — 6 lines but more readable
var hex = ""
for byte in bytes {
    let format = NSString(format: "%02x", byte)
    hex = "\(hex)\(format)"
}
hex

// Functionnal - 4 lines but weird
bytes.map({ (byte: Int) -> String in
    return NSString(format: "%02x", byte)
}).reduce("", combine: { (hex, byte) -> String in
    return hex+byte
})