public class func receipt(recipient: String, completionHandler completion:OneChatMessageCompletionHandler) {
        let messageID = OneChat.sharedInstance.xmppStream?.generateUUID()
        var received: DDXMLElement = DDXMLElement(name: "received", xmlns: "urn:xmpp:receipts")
        var message: DDXMLElement = DDXMLElement.elementWithName("message") as! DDXMLElement
        message.addAttributeWithName("to", stringValue: recipient)
        received.addAttributeWithName("id", stringValue: messageID)

        message.addChild(received)

        sharedInstance.didSendMessageCompletionBlock = completion
        OneChat.sharedInstance.xmppStream?.sendElement(message)
    }