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 *)manager
didFailWithError: (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];
}