title: How to know if a message is sent from an iPhone to the server?
body: <p>I have written an iPhone application communicating with a server. The app sends a message to the server and prints the result.</p>
  
  <p>Now I have a question: Is there a way to know if the message sent to the server came from an iPhone?</p>
  
  <p>I am asking this because I want to prevent attackers from sending messages from somewhere else and flooding the server.</p>