How can I track iPhone usage like the 'Moment' app does?

Question

How to track total usage of iPhone, even if our app is running in background(not forcefully terminated). Recently i have come across app, namely Moment this app does track your iPhone usages, even if this app is running in background. actually they are using location service to get execution time. my question is when they get execution time, how they can be sure if user's iPhone screen lock or unlock ?

i have code to check if screen is lock or unlock

-(void)registerAppforDetectLockState {

    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(@"unlock device");

            UIAlertView *errorAlert = [[UIAlertView alloc]
                                       initWithTitle:@"unlock device" message:@"test" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
            [errorAlert show];


        } else {
            NSLog(@"lock device");

            UIAlertView *errorAlert = [[UIAlertView alloc]
                                       initWithTitle:@"lock device" message:@"test" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
            [errorAlert show];

        }

    });
}

but this code is working only when app is running in foreground.

Answer 1

Your code is working only when app is running in foreground because when app goes in to background it is not called you have to use one of the background mode to wakeup your application can execute your code .