iOS requestStateForRegion 在 didStartMonitoringFor 之后返回 .unknown

Question

对为什么我的 AppDelegate CLLocationManager 有时无法成功确定 CLRegionState (CLRegionState.unknown) 感到困惑，即使我确保在 didStartMonitoringForRegion 之前不会调用 requestStateForRegion。似乎是某种竞争条件，我不明白我是如何处理的。

相关，得到CLRegionState.unknown怎么办？一直请求状态直到我得到什么？ (这看起来很糟糕)

应用委托(delegate):

- (BOOL)application:(UIApplication*)application didFinishLaunchingWithOptions:(NSDictionary*)launchOptions
{   
    self.locationManager = [[CLLocationManager alloc] init];
    [self.locationManager setDelegate:self];

    return [super application:application didFinishLaunchingWithOptions:launchOptions];
}

- (void)locationManager:(CLLocationManager *)manager didStartMonitoringForRegion:(nonnull CLRegion *)region {
    NSLog(@"%@", [NSString stringWithFormat:@"didStartMonitoringFor region with ID: %@", region.identifier]);
    // delay per https://stackoverflow.com/a/33288103/3380970
    double delayInSeconds = 2.0;
    dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
    dispatch_after(popTime, dispatch_get_main_queue(), ^(void) {
        [self.locationManager requestStateForRegion:region];
    });
}

- (void)locationManager:(CLLocationManager *)manager didDetermineState:(CLRegionState)state forRegion:(nonnull CLRegion *)region {
    NSLog(@"%@", [NSString stringWithFormat:@"didDetermineState from AppDelegate CLLocationManager: %@ (%ld)", region.identifier, (long)state ]);
    NSString *baseUrl = [self fetchBaseUrl];
    switch (state) {
        case CLRegionStateInside:
            NSLog(@"%@", @"Determined .inside state for geofence");
            [HelperFunctions postGeofenceTransitionWithBaseUrl:baseUrl region:region transitionType:1];
            break;
        default:
            break;
    }
}

摘要日志:

Adding geofence with ID: 5:90fd74e0-cbc7-dbe5-20fc-b870203055e1    
Adding geofence with ID: 8:d408f466-ea1b-6cbb-382f-f7567db61157
Adding geofence with ID: 7:ba97dda2-39a7-9b95-8ea9-ea183d69a858

didStartMonitoringFor region with ID: 5:90fd74e0-cbc7-dbe5-20fc-b870203055e1
didStartMonitoringFor region with ID: 8:d408f466-ea1b-6cbb-382f-f7567db61157
didStartMonitoringFor region with ID: 7:ba97dda2-39a7-9b95-8ea9-ea183d69a858

didDetermineState from AppDelegate CLLocationManager: 5:90fd74e0-cbc7-dbe5-20fc-b870203055e1 (0)
didDetermineState from AppDelegate CLLocationManager: 8:d408f466-ea1b-6cbb-382f-f7567db61157 (0)
didDetermineState from AppDelegate CLLocationManager: 7:ba97dda2-39a7-9b95-8ea9-ea183d69a858 (0)

谢谢

Answer 1

这是因为你在 block 中使用了入口参数region，而没有将其设为 block 变量。

在 - (void)locationManager:(CLLocationManager *)manager didStartMonitoringForRegion:(nonnull CLRegion *)region { 添加:

__block CLRegion *blockRegion = region;

并在 block 内使用 blockRegion。