Convert image to hex. NSImage to byte array

swift_hex.swift

// swift
var image = xxx
var rect = NSRect(x: 0, y: 0, width: image.size.width, height: image.size.height)
let cgImage = image.CGImageForProposedRect(&rect, context: nil, hints: nil)!.takeUnretainedValue()
let bitmapRep = NSBitmapImageRep(CGImage: cgImage)

if let imageData = bitmapRep.representationUsingType(NSBitmapImageFileType.NSPNGFileType, properties: [:]) {
    let len = imageData.length
    
    var bytes = [UInt8](count: len, repeatedValue: 0)
    imageData.getBytes(&bytes, length: len)
    
    var result = ""
    
    for i in 0...len - 1 {
        if i > 0 {
            result += ","
        }
        
        result += String(format: "0x%x", arguments: [bytes[i]])
    }
    
    println(result)
}

I use this code very helpful. can you show me how convert byte back to image in Mac OS X ? Thank you.