Swift string to data (bytes) and back

string_to_data_back.swift

// (string, swift, bytes, data, buffer, cstring)

print("--- using nulTerminated ---")
let x : String = "hello"
let buf = x.nulTerminatedUTF8
print(buf)

print("\n--- using [UInt8] ---")
let buf2 : [UInt8] = [UInt8](x.utf8)
print(buf2)

print("\n--- returning to string ---")
// Now for the other direction, as far as I can tell we need Foundation:
import Foundation
print(String(bytes: buf, encoding: NSUTF8StringEncoding))
print(String(bytes: buf2, encoding: NSUTF8StringEncoding))

// Notice that the first buf has an extra \0 in the string.  Apparently the
// String(bytes:encoding:) initialializer does not want a nul terminated UInt8
// array.  Can we print buffer directly as a UTF8 encoded string? Yes!
let ptr = x.nulTerminatedUTF8.withUnsafeBufferPointer {$0}
print(String.fromCString(UnsafePointer<Int8>(ptr.baseAddress)))

print("\n--- using NSData --- ")
// Getting NSData:
let data = x.dataUsingEncoding(NSUTF8StringEncoding)!
// Getting byte array:
let uint8Rep = [UInt8](UnsafeBufferPointer(start: UnsafePointer<UInt8>(data.bytes), count: data.length))
print(uint8Rep)
// Getting back to String:
print(String(data: data, encoding: NSUTF8StringEncoding))
// Getting back to String using byte array:
print(String(bytes: uint8Rep, encoding: NSUTF8StringEncoding))