位置背景模式在iOS上不起作用

Question

I am trying to enable background location mode in my application. I have enabled 'Location updates' background mode in my plist file. The app contains a timer that is updating every 15 seconds.

When the app is navigating to background, I am doing the following

- (void)applicationDidEnterBackground:(UIApplication *)application {
UIApplication*    app = [UIApplication sharedApplication];
self.bgTaskID = [app beginBackgroundTaskWithExpirationHandler:^{
        NSLog(@"background task %lu expired", (unsigned long)self.bgTaskID);
        [app endBackgroundTask:self.bgTaskID];
        self.bgTaskID = UIBackgroundTaskInvalid;
}];


 [NSTimer scheduledTimerWithTimeInterval:3 target:self selector:@selector(initializeLocationManager) userInfo:nil repeats:NO];

            if(self.timerLocationBackground)
            {
                [self.timerLocationBackground invalidate];
                self.timerLocationBackground = nil;
            }
            self.timerLocationBackground = [NSTimer scheduledTimerWithTimeInterval:15
                                                                            target:self
                                                                          selector:@selector(initializeLocationManager)
                                                                          userInfo:nil
                                                                           repeats:YES];}`

The initializeLocationManager is below

  -(void)initializeLocationManager
{
    if(!self.locationManager)
        self.locationManager = [[CLLocationManager alloc] init];
    else
        [self.locationManager stopUpdatingLocation];

    if ((![CLLocationManager locationServicesEnabled])
        || ([CLLocationManager authorizationStatus] == kCLAuthorizationStatusRestricted)
        || ([CLLocationManager authorizationStatus] == kCLAuthorizationStatusDenied))
    {
        //user has disabled his location
    }
    else
    {
        self.locationManager.delegate = self;
        self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
        self.locationManager.distanceFilter = kCLDistanceFilterNone;
        [self.locationManager setAllowsBackgroundLocationUpdates:YES];
        [self.locationManager startUpdatingLocation];
    }
}

When I navigate back to the application after 10 minutes for ex, my timer is being stopped at 3 min which is the time for the app to be suspended.

My code when the app get back to foreground is the below:

- (void)applicationWillEnterForeground:(UIApplication *)application {
// Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.

//
//Remove the baground task
//
if (self.bgTaskID != UIBackgroundTaskInvalid) {
    [[UIApplication sharedApplication] endBackgroundTask:self.bgTaskID];
    self.bgTaskID = UIBackgroundTaskInvalid;
}
[self.locationManager stopUpdatingLocation];

Any help?

Answer 1

Should be something like this. I've switched over to swift myself, so my objective-c might not be perfect.

- (void)applicationDidEnterBackground:(UIApplication *)application {

    [self keepAwakeInBackground ] ; 

    /// rest of your function to set up timers
}

- (void) keepAwakeInBackground {

    //Remove the old background task, if there was one
    if (self.bgTaskID != UIBackgroundTaskInvalid) {
        [[UIApplication sharedApplication] endBackgroundTask:self.bgTaskID];
        self.bgTaskID = UIBackgroundTaskInvalid;
    }
    /*
     *  You probably want something here to decide that the app should really be suspended here
     *  if ( ) return
     */

    // Set up new background task 
    UIApplication*    app = [UIApplication sharedApplication];
    self.bgTaskID = [app beginBackgroundTaskWithExpirationHandler:^{
        [self keepAwakeInBackground] 
    }];
}