This issue only occurred while debugging the app. I was finally able to resolve it by changing Edit Scheme - Run - Options - GPU Frame Capture from Automatically Enabled to OpenGL ES. Not sure why it worked.

Theoretically, this can work: Use BGTaskScheduler to set up notifications. You will be required to do some calculations to find when to trigger the background task. For example, you want to trigger the notification the first notification at 14:00 and post that, every 5 minutes until notification is dismissed. You will schedule the background task for 13:55 and inside the background task set up the repeating notification with the time interval of 5 minutes. Hope this helps.