I want a timer to decreasing become time from current time. i.e. this is my beginning time ’05:23:23′ and if the the current time or DateTime.now() is going up my time should goes to come down, and if I am going to close the app for 05min and 13sec, and opening the app’ timer should not start from the beginning ’05:23:23′ the up should start from the passed times ’05:18:10′.