iPhone GPS问题模拟器没有反应

我试图创建简单的GPS应用程序,只是为了在模拟器中显示简单的数据。我没有错误,只是无法获取数据。”DidfailWitherRor“方法是我唯一能工作的方法:),这是代码:

- (void)viewDidLoad 
{  
 [super viewDidLoad];

 lm = [[CLLocationManager alloc] init];
 if([CLLocationManager locationServicesEnabled])
 {
  lm.delegate = self;
  lm.desiredAccuracy = kCLLocationAccuracyBest;
  //lm.distanceFilter = 1000.0f;
  [lm startUpdatingLocation];
 }

}


- (void) locationManager: (CLLocationManager *) manager
didUpdateToLocation: (CLLocation *) newLocation
fromLocation: (CLLocation *) oldLocation{
 NSString *lat = [[ NSString alloc] initWithFormat:@"%g", newLocation.coordinate.latitude];
 txtLatitude.text = lat;

 NSString *lng = [[NSString alloc] initWithFormat:@"%g", newLocation.coordinate.longitude];
 txtLongitude.text = lng;

 NSString *acc = [[NSString alloc] initWithFormat:@"%g", newLocation.horizontalAccuracy];
 txtAccuracy.text = acc;

 [acc release];
 [lat release];
 [lng release];
}
- (void) locationManager:(CLLocationManager *)manager 
didFailWithError: (NSError *) error
{
 NSString *msg = [[NSString alloc] initWithString:@"Error obtaining location"];
 UIAlertView *alert = [[ UIAlertView alloc] initWithTitle:@"Error" 
              message:msg 
             delegate:nil 
             cancelButtonTitle:@"Done" 
             otherButtonTitles:nil];
 [alert show];
 [msg release];
 [alert release];
}