Mapkit adding new annotation and remove the old - ios

Question

i want the map to get the location of the user and he can change the location by taping on the map. The problem is when tap on location the method (void)mapView:(MKMapView *)mapView_ didUpdateUserLocation , called and the map show both the current location and the location he tapped in!! i want only one location >>>
here is the code
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
self.mapView.delegate = self;
locationManager = [[CLLocationManager alloc] init];
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleSingleTap:)];
[mapView addGestureRecognizer:singleTap];
}
- (void)mapView:(MKMapView *)mapView_ didUpdateUserLocation:(MKUserLocation *)userLocation
{
locationManager.delegate = self;
locationManager.desiredAccuracy = kCLLocationAccuracyBest;
[locationManager startUpdatingLocation];
longitudeLabel.text = [NSString stringWithFormat:#"%.8f", userLocation.coordinate.longitude];
latitudeLabel.text = [NSString stringWithFormat:#"%.8f", userLocation.coordinate.latitude];
MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(userLocation.coordinate, 800, 800);
[mapView setRegion:[mapView regionThatFits:region] animated:YES];
// Add an annotation
MKPointAnnotation *point = [[MKPointAnnotation alloc] init];
point.coordinate = userLocation.coordinate;
point.title = #"Where am I?";
point.subtitle = #"I'm here!!!";
[mapView addAnnotation:point];
}
- (void)handleSingleTap:(UIGestureRecognizer *)sender
{
CLLocationCoordinate2D coord = [mapView convertPoint:[sender locationInView:mapView] toCoordinateFromView:mapView];
NSLog(#"Map touched %f, %f.", coord.latitude, coord.longitude);
longitudeLabel.text = [NSString stringWithFormat:#"%.8f", coord.longitude];
latitudeLabel.text = [NSString stringWithFormat:#"%.8f", coord.latitude];
MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(coord, 800, 800);
[mapView setRegion:[mapView regionThatFits:region] animated:YES];
// Add an annotation
MKPointAnnotation *point = [[MKPointAnnotation alloc] init];
point.coordinate = coord;
point.title = #"Where am I?";
point.subtitle = #"I'm here!!!";
[mapView removeAnnotations:[mapView annotations]];
[mapView addAnnotation:point];
}

Answer 1

Firstly, on ask one question on each page. If I answer question 2 right and someone else answers question 1 right, which one gets marked as the right answer?
Secondly, the method didUpdateUserLocation is called by iOS when it gets new information about where the device is. You don't need to add a new annotation there or you'll end up with lots of annotations for every time the device moves. If you want to show the user's current location call mapView.showsUserLocation = YES;. Once the user has tapped and you've created a new annotation, you can turn the userLocation off by setting it to NO.