Lock Unlock events iphone

You can use Darwin notifications, to listen for the events. From my testing on a jailbroken iOS 5.0.1 iPhone 4, I think that one of these events might be what you need:

com.apple.springboard.lockstate
com.apple.springboard.lockcomplete

Note: according to the poster’s comments to a similar question I answered here, this should work on a non-jailbroken phone, too.

To use this, register for the event like this (this registers for just the first event above, but you can add an observer for lockcomplete, too):

CFNotificationCenterAddObserver(CFNotificationCenterGetDarwinNotifyCenter(), //center
                                (void*)self, // observer (can be NULL)
                                lockStateChanged, // callback
                                CFSTR("com.apple.springboard.lockstate"), // event name
                                NULL, // object
                                CFNotificationSuspensionBehaviorDeliverImmediately);

where lockStateChanged is your event callback:

static void lockStateChanged(CFNotificationCenterRef center, void *observer, CFStringRef name, const void *object, CFDictionaryRef userInfo) {
    NSLog(@"event received!");
    if (observer != NULL) {
        MyClass *this = (MyClass*)observer;
    }

    // you might try inspecting the `userInfo` dictionary, to see 
    //  if it contains any useful info
    if (userInfo != nil) {
        CFShow(userInfo);
    }
}

The lockstate event occurs when the device is locked and unlocked, but the lockcomplete event is only triggered when the device locks. Another way to determine whether the event is for a lock or unlock event is to use notify_get_state(). You’ll get a different value for lock vs. unlock, as described here.