You can enable the userlocation by this:
mapView.showsUserLocation = YES;
if you want to center on this location:
[mapView setCenterCoordinate:mapView.userLocation.location.coordinate animated:YES];
if you are using:
- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation
{
if ([annotation isKindOfClass:[MKUserLocation class]]) {
return nil;
}
// etc...
}