Understanding iBeacons in iOS: didDetermineState and didEnterRegion events

问题

Part one:

I have written the following code to monitor iBeacons. I would like to detect the didEnterRegion and didExitRegion event. However it never happens. Would you be able to take a look at the code and suggest what could be missing?

I use the Apple AirLocate sample code to configure one device as iBeacon and perform the following steps to test my code:

Steps:

compile and execute AirLocate sample code on device B
compile and execute this code on device A
in device B use AirLocate app to configure device as iBeacon choosing the following UUID: "74278BDA-B644-4520-8F0C-720EAF059935"

Results:

state inside message

Expected results:

state inside message
did enter region

Why is that?

Those are my plist entries:

Code:

#import "BeaconMonitoring.h"

@implementation BeaconMonitoring

- (instancetype)init
{
    self = [super init];
    if (self) {
        self.locationManager = [[CLLocationManager alloc] init];

        if([self.locationManager respondsToSelector:@selector(requestAlwaysAuthorization)]) {
            [self.locationManager requestAlwaysAuthorization];
        }

        self.locationManager.delegate = self;
        self.locationManager.pausesLocationUpdatesAutomatically = NO;

        self.monitoredRegions = [[NSMutableArray alloc] initWithCapacity:10];
    }
    return self;
}

- (void) startRangingForBeacons{
    NSLog(@"in startRangingForBeacons");
    [self.locationManager startUpdatingLocation];
    [self startMonitoringForRegion:[[NSUUID alloc] initWithUUIDString:@"74278BDA-B644-4520-8F0C-720EAF059935"] :@"b"];
}

- (void) startMonitoringForRegion:(NSUUID*)beaconUUID :(NSString*)regionIdentifier{
   /**
    Alternatively:
    CLBeaconRegion *beaconRegion = [[CLBeaconRegion alloc] initWithProximityUUID:@"xxxx"
    major:10
    minor:20
    identifier:@"name"]
    **/

    // Override point for customization after application launch.
    CLBeaconRegion *beaconRegion = [[CLBeaconRegion alloc] initWithProximityUUID:beaconUUID identifier:regionIdentifier];

    beaconRegion.notifyEntryStateOnDisplay = NO;
    beaconRegion.notifyOnEntry = YES;
    beaconRegion.notifyOnExit  = YES;

    [self.locationManager startMonitoringForRegion:beaconRegion];
    [self.locationManager startRangingBeaconsInRegion:beaconRegion];
    [self.monitoredRegions addObject:beaconRegion];
}

- (void) stopRangingForbeacons{
    NSLog(@"in stopRangingForbeacons");
    [self.locationManager stopUpdatingLocation];

    for (int i=0; i < [self.monitoredRegions count]; i++) {
        NSObject * object = [self.monitoredRegions objectAtIndex:i];

        if ([object isKindOfClass:[CLBeaconRegion class]]) {
            CLBeaconRegion * region = (CLBeaconRegion*)object;
            [self.locationManager stopMonitoringForRegion:region];
            [self.locationManager stopRangingBeaconsInRegion:region];
        }
        else{
            NSLog(@"Serious error, should never happen!");
        }
    }
}


#pragma CLLocationManagerDelegate

-(void)locationManager:(CLLocationManager *)manager didEnterRegion:(CLRegion *)region {
    [manager startRangingBeaconsInRegion:(CLBeaconRegion*)region];
    [self.locationManager startUpdatingLocation];
    NSLog(@"You entered the region.");
}

-(void)locationManager:(CLLocationManager *)manager didExitRegion:(CLRegion *)region {
    [manager stopRangingBeaconsInRegion:(CLBeaconRegion*)region];
    [self.locationManager stopUpdatingLocation];


    NSDictionary * notificationData = @{ @"value" : @"exitedRegion"};
    [[NSNotificationCenter defaultCenter] postNotificationName:@"dataUpdate" object:nil userInfo:notificationData];

    NSLog(@"You exited the region.");
    // [self sendLocalNotificationWithMessage:@"You exited the region."];
}

- (void) locationManager:(CLLocationManager *)manager didDetermineState:(CLRegionState)state forRegion:(CLRegion *)region
{
    NSLog(@"did determine state");

    switch (state) {
        case CLRegionStateInside:
            NSLog(@"state inside");
            break;
        case CLRegionStateOutside:
            NSLog(@"state outside");
            break;
        case CLRegionStateUnknown:
            NSLog(@"state unknown");
            break;
        default:
            NSLog(@"Default case: Region unknown");
            break;
    }
}

-(void)locationManager:(CLLocationManager *)manager didRangeBeacons:(NSArray *)beacons inRegion:(CLBeaconRegion *)region {

    NSLog(@"Did range %lu beacon in region %@", (unsigned long)[beacons count], region.identifier);

    NSString * visibleInformation = [NSString stringWithFormat:@"(%lu)", (unsigned long)[beacons count]];

    for (int i=0; i<[beacons count]; i++) {
        CLBeacon *beacon = [beacons objectAtIndex:i];

        if ([beacons count] == 1) {
            NSNumber * distance =  [NSNumber numberWithFloat:beacon.accuracy];
            visibleInformation = [NSString stringWithFormat:@"%i-%i is %f", beacon.major.intValue, beacon.minor.intValue, distance.doubleValue];
        }
        else{
            visibleInformation = [visibleInformation stringByAppendingString:[NSString stringWithFormat:@" %i-%i ", beacon.major.intValue, beacon.minor.intValue]];
        }
    }
}

@end

Part two:

I had a look at the AirLocate source code to understand if there was something that I had to trigger in the state inside message to get the monitoring working properly. However I found that the ** didDetermineState** method is implemented in the AppDelegate.

Why is that?

- (void)locationManager:(CLLocationManager *)manager didDetermineState:(CLRegionState)state forRegion:(CLRegion *)region
{
    /*
     A user can transition in or out of a region while the application is not running. When this happens CoreLocation will launch the application momentarily, call this delegate method and we will let the user know via a local notification.
     */
    UILocalNotification *notification = [[UILocalNotification alloc] init];

    if(state == CLRegionStateInside)
    {
        notification.alertBody = NSLocalizedString(@"You're inside the region", @"");
    }
    else if(state == CLRegionStateOutside)
    {
        notification.alertBody = NSLocalizedString(@"You're outside the region", @"");
    }
    else
    {
        return;
    }

    /*
     If the application is in the foreground, it will get a callback to application:didReceiveLocalNotification:.
     If it's not, iOS will display the notification to the user.
     */
    [[UIApplication sharedApplication] presentLocalNotificationNow:notification];
}