This is a sample iOS application to monitor directory changes in the background.

The video depicts adding/removing files using iTunes File sharing feature. iPhone is running iOS10.

YouTube video

Here's a short preview if you can't open YouTube for some reason:

• Background execution is achieved by requesting 'Always' location updates.
• File changes are tracked with GCD descriptor dispatch source.
• Notifications are reported using local notifications.

There are a few things that can be improved. However, since this is only a sample, they are left out.

• Waiting for changes to finish. There are several use cases where reporting right away does not make much sense

  • When several files are added or removed, there is a notification for each one of them
  • When a large file is added, notification is reported before the file has been uploaded

• Supporting UNUserNotificationCenter

  • UILocalNotification is deprecated in iOS10, but still works
  • NotificationWithLNAndUNC directory contains an attempt to use UNC if it's supported, but since the async nature of UNUserNotificationCenter getNotificationSettingsWithCompletionHandler: ruins the pretty interface of Notification class, I decided to stay with UILocalNotification

Here are some of the docs I used to implement the sample.

• Directory monitoring with GCD
  • https://habrahabr.ru/post/191868/
  • https://www.cocoanetics.com/2013/08/monitoring-a-folder-with-gcd/
• iOS background execution
  • https://habrahabr.ru/post/271505/
  • https://github.com/vaskravchuk/BGModesTest