ios - How to call a mapview current location zoom in method from appdelegate correctly?

Question

I have tried using this method, but for some reason it wont zoom in on the current location. Is there something I am doing wrong?

Appdelegate.m

 -(void)handleNetworkChange
{
    self.reachability = [Reachability reachabilityForInternetConnection];
    [self.reachability startNotifier];
    NetworkStatus remoteHostStatus = [self.reachability currentReachabilityStatus];
    MapViewController *mapViewController = [[MapViewController alloc]init];
    if(remoteHostStatus == NotReachable)
    {
        self.internetReachable = NO;
    }
    else
    {
        self.internetReachable = YES;
        [mapViewController userLocation];
    }    
}

MapViewController.m

-(void)userLocation
{
    MKCoordinateRegion mapRegion;
    mapRegion.center.latitude = self.mapView.userLocation.coordinate.latitude;
    mapRegion.center.longitude = self.mapView.userLocation.coordinate.longitude;
    mapRegion.span.latitudeDelta = 0.2;
    mapRegion.span.longitudeDelta = 0.2;
    [self.mapView setRegion:mapRegion animated:YES];
}