Detecting iPhone lock and unlock when app is in the background

Currently it looks like we can only detect screen lock/unlock when the app is in the foreground.

How are you doing this?

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Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

Hey,

I have the same question, i use this code in Objective C :

int notify_token;
    notify_register_dispatch("com.apple.springboard.lockstate", &notify_token,dispatch_get_main_queue(), ^(int token) {
        uint64_t state = UINT64_MAX;
        notify_get_state(token, &state);
      
        /
      
        if(state == 0) {
            NSLog(@"Unlocked");
            /
          
        } else {
            NSLog(@"Locked");
            /
        }
      
    });

I launch it in my AppDelegate didFinishLaunchingWithOptions method.

In foreground the detection works perfectly but when the app is in background it doesn't work anymore. Any idea on how to make this work in background ?

i use this code in Objective C :

This notify key is not considered API. Apple’s general rule with stringly typed APIs is that you must only use Apple keys if they are explicitly documented. In the case of the Darwin notifications API, this means the key must be listed in

<notify_keys.h>

AFAIK there’s no public API for determine the screen lock state of the device. [You can be notified of data protection state changes, via

UIApplicationProtectedDataWillBecomeUnavailable

UIApplicationProtectedDataDidBecomeAvailable

Any idea on how to make this work in background ?

The Darwin notifications API will not resume (or relaunch) your process if it’s suspended (or terminated) when the notification is triggered. There’s no general way to do that.

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—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

Thanks for your answer.

UIApplicationProtectData is working fine but it's not exactly what i'm looking for, i need more precision.

Do you know if there is a way to check if the user is using his phone while my app is in background ? For exemple he's on his message or email ?

Thanks.

Do you know if there is a way to check if the user is using his phone while my app is in background ?

Not in general.

For exemple he's on his message or email ?

And definitely not in this case. There have been hack-ish ways to do this in the past but they generally get closed off by the sandbox as a privacy bug.

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—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

It will work Background and foreground also

Write this code in AppDelegate didFinishLaunchingWithOptions Method:

self.backgroundTaskIdentifier =

[[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{

[[UIApplication sharedApplication] endBackgroundTask:self.backgroundTaskIdentifier];

}];

[self registerAppforDetectLockState];

-------------------------------------------------------

-(void)registerAppforDetectLockState {

/

notify_register_dispatch("com.apple.springboard.lockstate", &notify_token,dispatch_get_main_queue(), ^(int token) {

uint64_t state = UINT64_MAX;

notify_get_state(token, &state);

if(state == 0) {

NSLog(@"unlock device");

} else {

NSLog(@"lock device");

}

NSLog(@"com.apple.springboard.lockstate = %llu", state);

UILocalNotification *notification = [[UILocalNotification alloc]init];

notification.repeatInterval = NSCalendarUnitDay;/

[notification setAlertBody:@"Hello world!! I come becoz you lock/unlock your device :)"];

notification.alertAction = @"View";

notification.alertAction = @"Yes";

[notification setFireDate:[NSDate dateWithTimeIntervalSinceNow:1]];

notification.soundName = UILocalNotificationDefaultSoundName;

[notification setTimeZone:[NSTimeZone defaultTimeZone]];

[[UIApplication sharedApplication] presentLocalNotificationNow:notification];

});

}

@gupta163 and other folks, please stop advising people to use undocumented notification keys. As I discussed in my 23 Jan 2017 post, any notification key that’s not explicitly documented by Apple is considered private API.

Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

Using protectedDataWillBecomeUnavailableNotification solved partially the problem as this notification does not always arrive in time as soon as the device is locked. Observing didEnterBackgroundNotification and willEnterForegroundNotification to request/terminate background execution time solved the notification delivery problem. In addition verifying that applicationState == .background in protectedDataWillBecomeUnavailableNotification makes it more stable.

This notify key is not considered API. Apple’s general rule with stringly typed APIs is that you must only use Apple keys if they are explicitly documented.

Where exactly are them documented?