takePictureCallback.swift

let picId = packet["pic_id"] as! String
let data  = packet["data"] as! String
let pos   = packet["pos"] as! Int
let total = packet["size"]as! Int

// Initialize picture if this is the first packet
if pos == 0 {
    let timestamp = packet["pic_date"] as! Double
    picture = Picture(name: picId, date: NSDate(timeIntervalSince1970: timestamp / 1000.0))
}

// finalize the picture and call completion handler if this is the last packet
if pos == total - 1 {
    picture.addPacket(data, finalPacket: true)
    pictureImage.image = picture.getImage()
} else {
    picture.addPacket(data, finalPacket: false)
}