Is there a away to detect the event when iOS device goes to sleep mode (when the screen gets blackened)?

Question

I wanted to detect two events :

1. Device gets locked/unlocked.
2. Device goes to sleep and the screen blackens.

First one I have been able t

Answer 1

You can also subscribe for a notification: "com.apple.springboard.lockstate" and use API SBGetScreenLockStatus to determine status whether device is locked or not.