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];
}

is your method userLocation getting called from app delegate — Gajendra Rawat, Mar 10 '14 at 15:50
where do you show (present) the `mapViewController`, and why you create an instance of `MapViewController` every time `handleNetworkChange` method is called? — iOS Dev, Mar 10 '14 at 15:55
I only show instances that way as an example, but the way I show mapviewcontroller is through navigation controller not through appdelegate. — user3249524, Mar 10 '14 at 15:59
First you can log the mapView userLocation coordinates, to see if there are the right ones, then try to change deltas from 0.2 to 0.005. — iOS Dev, Mar 10 '14 at 16:06
Regardless of the "Reachability logic", is showsUserLocation set to YES? But most important: `mapView.userLocation` should be accessed in the didUpdateUserLocation delegate method so you can be reasonably sure the map view actually has a location. Outside of that delegate method, you must first check if `mapView.userLocation.location` is `nil`. Additionally, if you use the userTrackingMode, you shouldn't have to worry about this in first place. — , Mar 10 '14 at 17:01
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score 0 · Answer 1 · answered Mar 10 '14 at 16:35

I would simply use NSNotificationCenter. you set a listener that waits for a post notification, once the post norification is received it will fire a selector

here is how to do it (very simple actually)

This needs to go in your view controller where you present the map, best in viewDidLoad

[[NSNotificationCenter defaultCenter] addObserver:self
        selector:@selector(runThisFunctionWhenReady:) 
        name:@"TestNotification"
        object:nil];

he zoom method should be placed in the same viewcontroller - like so:

-(void)runThisFunctionWhenReady
{
   // Zoom the map and other funky stuff
}

Now, from anywhere in the app (delegate included) you can fire this by posting a notification like this:

 [[NSNotificationCenter defaultCenter] 
        postNotificationName:@"TestNotification" 
        object:self];

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

1 Answers1