我正在尝试设置一个小型地理围栏（100 米），以便在用户离开家时提醒他们。为此，我请求用户当前位置，如下所示：
- (void)requestUsersCurrentLocation
{
if (self.locationManager == nil) self.locationManager = [[CLLocationManager alloc] init];
self.locationManager.delegate = self;
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
self.locationManager.distanceFilter = 100;
[self.locationManager startUpdatingLocation];
}
使用 CLLocationManager 的委托方法，我检查应用程序是否能够确定用户的当前位置。在我的测试中，这可以正常工作，并且应用程序继续调用我的attemptToRegisterGeofenceAlertForLocation:方法
- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
CLLocation *location = [locations lastObject];
NSDate *eventDate = location.timestamp;
NSTimeInterval howRecent = [eventDate timeIntervalSinceNow];
if (abs(howRecent) < 15.0)
{
[self.locationManager stopUpdatingLocation];
if([self attemptToRegisterGeofenceAlertForLocation:location])
{
[[NSNotificationCenter defaultCenter] postNotificationName:kGeofenceSetupSuccess object:nil];
}
else
{
[[NSNotificationCenter defaultCenter] postNotificationName:kGeofenceSetupFailure object:nil];
}
}
}
到目前为止，一切都很好。这是我的自定义函数，用于在用户当前位置周围注册一个相对较小的地理围栏：
- (BOOL)attemptToRegisterGeofenceAlertForLocation:(CLLocation *)location
{
// Do not create regions if support is unavailable or disabled
if (![CLLocationManager regionMonitoringAvailable]) return NO;
// Check the authorization status
if (([CLLocationManager authorizationStatus] != kCLAuthorizationStatusAuthorized) && ([CLLocationManager authorizationStatus] != kCLAuthorizationStatusNotDetermined)) return NO;
// Clear out any old regions to prevent buildup.
if ([self.locationManager.monitoredRegions count] > 0)
{
for (id obj in self.locationManager.monitoredRegions)
{
[self.locationManager stopMonitoringForRegion:obj];
}
}
// If the overlay's radius is too large, registration fails automatically,
// so clamp the radius to the max value.
CLLocationDegrees radius = 100; // meters?
if (radius > self.locationManager.maximumRegionMonitoringDistance)
{
radius = self.locationManager.maximumRegionMonitoringDistance;
}
// Create the region to be monitored.
CLRegion *region = [[CLRegion alloc] initCircularRegionWithCenter:location.coordinate radius:radius identifier:kGeofenceIdentifier];
[self.locationManager startMonitoringForRegion:region];
return YES;
}
当用户退出地理围栏区域时，我会这样回应：
- (void)locationManager:(CLLocationManager *)manager didExitRegion:(CLRegion *)region
{
if([region.identifier isEqual:kGeofenceIdentifier])
{
if([[UIApplication sharedApplication] applicationState] == UIApplicationStateBackground)
{
// Fire a UILocationNotification
}
else
{
// Fire a UIAlertView
}
}
}
我已经确定该应用程序能够获取用户位置并且地理围栏已正确注册，但是我无法在实际设备（支持 3G 的 iPhone）上触发它。我离开了地理围栏区域，走了几英里，却没有收到任何通知。通过彻底改变我的位置，我成功地在模拟器中接收到警报。
我究竟做错了什么？