ios 里如何判断当前应用的定位服务是否可用

如何在某个程序里面判定当前应用程序的定位服务是否可用，其实没有什么简单的方法。

这个[CLLocationManager locationServicesEnabled]检测的是整个iOS系统的位置服务开关，无法检测当前应用是否被关闭，只能通过CLLocationManagerDelegate的locationManager:didFailWithError:方法去检测：

- (void)locationManager: (CLLocationManager *)managerdidFailWithError: (NSError *)error {        NSString *errorString;    [manager stopUpdatingLocation];    NSLog(@"Error: %@",[error localizedDescription]);    switch([error code]) {        case kCLErrorDenied:            //Access denied by user            errorString = @"Access to Location Services denied by user";            //Do something...            break;        case kCLErrorLocationUnknown:            //Probably temporary...            errorString = @"Location data unavailable";            //Do something else...            break;        default:            errorString = @"An unknown error has occurred";            break;    }}UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" message:errorString delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];[alert show];[alert release];}