title: Share data across multiple apps on iOS
body: <p>I know there are quite a few threads on this, but it seems none of them would satisfy what I am trying to look for. Here's my constraints:</p>
  
  <ul>
  <li>not a hack that uses private API/framework or undocumented
  directory access that would run the risk of app being rejected
  because of that</li>
  <li>being able to share data across different
  vendors / app developers </li>
  <li>data can persist outside the lifecycle
  of the app (even after app is deleted)</li>
  </ul>
  
  <p>UPDATED: I was in general trying to stay away from using a 3rd party cloud-based service to achieve the goal as this would introduce additional external dependency. But if I have to, I was hoping it could satisfy this one constraint </p>
  
  <ul>
  <li>being able to tell which iOS device it is communicating with. It shouldn't have to uniquely identify the device (which will go into that evil UDID discussion route as we all experienced ). But as long as it can differentiate among different iOS devices it should be fine.</li>
  </ul>