CLLocationManager monitoredRegions返回nil

Question

我正在开发一款iPhone应用程序，我必须监控超过20个区域。

开发环境：Xcode（版本8.3.2）

IOS 10.3

请看下面的代码：

我初始化我的位置管理员：

- (id)init {
    self = [super init];
    if(self != nil) {
        self.locationManager = [[CLLocationManager alloc] init];
//        self.locationManager.distanceFilter = 100; // meters
        self.locationManager.allowsBackgroundLocationUpdates = YES;
        self.locationManager.delegate = self;
        self.locationManager.desiredAccuracy = kCLLocationAccuracyBestForNavigation;
    }
    return self;
}

然后我开始使用以下代码更新位置：

- (void)startUpdatingLocation
{
    NSLog(@"Starting location updates");
    // Turn on location updates for accuracy and so processing can happen in the background.
    [self.locationManager stopUpdatingLocation];
    [self.locationManager startUpdatingLocation];

    // Turn on significant location changes to help monitor the current region.
    [self.locationManager startMonitoringSignificantLocationChanges];



}


- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{

    if (locations.count > 0) {
        //stop all monitored region

        for (CLRegion *monitored in [self.locationManager monitoredRegions]){
            [self.locationManager stopMonitoringForRegion:monitored];
        }

        CLLocation *location = locations[0];
        NSArray *allGeoFences = [self getAllGeoFences];

        NSMutableArray *sortedFences = [[NSMutableArray alloc] init];
        // add distance to each fence to be sorted
        for (locationInterface *geofence in allGeoFences) {
            // create a CLLocation object from my custom object
            //CLLocationCoordinate2D coordinate = CLLocationCoordinate2DMake(geofence.region., geofence.longitude);
            CLLocation *fenceLocation = [[CLLocation alloc] initWithLatitude:
                                         geofence.region.center.latitude
                                         longitude:geofence.region.center.longitude];
            // calculate distance from current location
            CLLocationDistance distance = [location distanceFromLocation:fenceLocation];
            // save distance so we can filter array later
            geofence.distance = distance;
            [sortedFences addObject:geofence];
        }

        // sort our array of geofences by distance and add we can add the first 20

        NSSortDescriptor *sortByName = [NSSortDescriptor sortDescriptorWithKey:@"distance" ascending:YES];
        NSArray *sortDescriptors = [NSArray arrayWithObject:sortByName];
        NSArray *sortedArray = [sortedFences sortedArrayUsingDescriptors:sortDescriptors];



        //get nearest 20 regions

        NSMutableArray *nearestRegions = [[NSMutableArray alloc] init];
        for (int i = 1; i <= 20; i++) {
            [nearestRegions addObject:sortedArray[i]];
            locationInterface* monitorRegion = sortedArray[i];
            [self.locationManager startMonitoringForRegion:monitorRegion.region] ;
        }

    }
}

当我收到didUpdateLocations时，首先我停止所有受监控的区域，之后我找到20个最近的位置，并开始监控最近的20个位置。

我面临的问题是 monitoredRegions 总是返回nil。这就是为什么我无法停止监控区域，我的新添加的区域被忽略。请帮助我。