We have developed an iOS application which allows users to set some alarms based on the time given. These set alarms are displayed in my "Alarm scheduler" screen of my application. The local notification will trigger this alarm when set time is reached.

Now if user changes his timezone say from EDT to PDT, then the "Alarm scheduler" screen is showing the alarm time properly, but my local notification is not getting triggered.

For example suppose its 8:55 AM EDT and user has set the alarm to trigger at 9:00 AM EDT. Now my "Alarm scheduler" screen will show the alarm time as "9:00 AM", now if user changes the timezone to PDT, then the "Alarm scheduler" page will display the alarm time as "6:00 AM" which is correct and users phone will show the time as "5:55 AM". However after 5 mins when "6:00 AM PDT" is reached the local notification is not getting triggered.

Can some one advice how to achieve this?