title: Prevent my app to sleep when device goes to sleep mode
body: <p>I have written an app that should be running continually event if device goes to sleep mode.I have tried many things like services (with startForground also) , alarm manager and persistant="true", but when device go to sleep (by user or by device) , my app is terminated.and even PowerManager does not work too.</p>
  
  <p>There is an option in device setting that is 'Keep running after screen off' (in huawei device : setting > app > my app options > battery > Keep running after screen off). So when this option is active , the app is running for ever.I want implement something like this in my app programitically.</p>
  
  <p>I saw some apps that implemented this , but I dont know how.
  So how can I do that?</p>