title: iOS Notification when App is in Background
body: <p>i want to know if it is possible to launch a background process in iOS. In my background process every 30 minutes there should a function get called, in order to check in my database if there are new messages, etc in order to send a notification. I don't want to implement push notifications. 
  I don't know where to implement this feature, and if there are override functions e.g. in the AppDelegate.</p>
  
  <p>Thanks for your help, 
  hannes</p>