title: Keep NSTimer running when app is in background
body: <p>I hope there's an expert out there who can help me with this:</p>
  
  <p>I googled it for hours, but could not find any information if there is any way to keep a running NSTimer active when the app is running in the background ?</p>
  
  <p>The problem scenario is I need to set a countdown timer on button click. Time left is shown (02:34:45) as title of button. how do my timer is keep on running when application enters into background or it is suspended . Please help me how i can maintain the time left for alarm, what are the values selected for alarm ( like 2 hours , 3 minutes )</p>
  
  <p>Thanks for any help!</p>