How to Distinguish Between Locking the Device and Sending an App to Background

Is it possible to distinguish between locking the device and sending an app to background?

iOS 6

In my preliminary testing via the simulator, checking the application state with

[[UIApplication sharedApplication] applicationState]

in either

- (void)applicationWillEnterForeground:(UIApplication *)application

- (void)applicationDidEnterBackground:(UIApplication *)application

allows you to differentiate between a call to lock the device and just switching back to the homescreen. A lock screen will return 1 (UIApplicationStateInactive), whereas a home button press will register as a 2 (UIApplicationStateBackground).

It seems consistent and should work on an iOS device just as reliably as it does in the simulator.

iOS 7

The iOS 6 method no longer works in iOS 7. In order to do this now, you have to utilize CFNotificationCenter and listen for a darwin notification (labeled: com.apple.springboard.lockcomplete). You can find the github repo with the sample project here: https://github.com/binarydev/ios-home-vs-lock-button

Credit for the iOS 7 fix goes out to wqq

Can we detect whether a user left through the home button or lock button without listening to darwin notifications?

After searching through the documentation from apple and digging through a ton of threads I think I might have stumbled upon the solution.

As far as I know this is currently the only way of detecting whether a user left through the home button or lock button (I don't believe this works on the simulator you have to try it on an actual phone).

Inside of this delegate (And it will only work when called in this delegate)

func applicationDidEnterBackground(_ application: UIApplication) {

}

You can call this little snippet here:

func DidUserPressLockButton() -> Bool {
    let oldBrightness = UIScreen.main.brightness
    UIScreen.main.brightness = oldBrightness + (oldBrightness <= 0.01 ? (0.01) : (-0.01))
    return oldBrightness != UIScreen.main.brightness
}

Usage:

func applicationDidEnterBackground(_ application: UIApplication) {
    if (DidUserPressLockButton()) {
        //User pressed lock button
    } else {
        //user pressed home button
    }
}

EXPLANATION:

It seems that apple only lets you change the screen brightness from applicationDidEnterBackground when the user left through the lock button and not the home button. So the idea is to change the screen brightness with a miniscule amount and check to see if it was able to be changed. This seems kinda hacky but I've heard that this is actually working as intended. As far as testing it goes it seems to be working 100% of the time. I could not find any issues with this except for users that really do want to change the brightness of the screen. I hope someone else can find something less hacky and more concrete.

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