how to implement ongoing Local notification?

• In my application, i want to implement "Ongoing" local notification (which is not removed by user and continue display in notification) which is fired when any timer set from my application.
• So my requirement is when user tap on notification user redirect in application that is working fine. But when user again check notification window that notification will remove from notification window. But i want to stay that notification in notification window until timer is out from my application.
• So how can i implement this functionality.
• Or if this is not possible then PLEASE give me apple document link and proper reason.
• And please give me alternative solution how can i achieved this functionality ?

Thanks in advance.