Objective-c – MKMapView: On startup user location -> zooming

iphoneobjective c

I have a MKMapView and in the Map View "Show User Location" is set. The question if the app should use my location, I say yes. Then I see the blue bullet and I can zoom to the current location.

I read many other posts about this, but nothing solve the problem, that the user location won't zoom in automatically.

I want to have a zoom on startup if the user allows access the location, otherwise a defined coordinate should zoom in. (after, is the use allows the location, it can be updated, but should not set the center to the user location everytime I get updates on the location).

What are the steps to implement this behavior? I tried for example this: How do I zoom an MKMapView to the users current location without CLLocationManager? with the KVO but it does not work…

I hope someone has an idea?

Best Regards, Tim

Best Answer

Have you tried the delegate method mapView:didUpdateUserLocation:?

I used something like this in my code:

In the .h file:

@property (nonatomic, retain) CLLocation* initialLocation;

And in the .m file:

- (void)mapView:(MKMapView *)mapView didUpdateUserLocation:(MKUserLocation *)userLocation
{
    if ( !initialLocation )
    {
        self.initialLocation = userLocation.location;

        MKCoordinateRegion region;
        region.center = mapView.userLocation.coordinate;
        region.span = MKCoordinateSpanMake(0.1, 0.1);

        region = [mapView regionThatFits:region];
        [mapView setRegion:region animated:YES];
    }
}

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Here's an example of zooming programatically (there is no way in IB to do this):

   MKCoordinateRegion region;
   MKCoordinateSpan span;
   span.latitudeDelta=0.02 / 10; // zoom level
   span.longitudeDelta=0.02 / 10;

   CLLocationCoordinate2D location;
   location.latitude = latitude; // set these var's first!
   location.longitude = longitude;

   region.span=span;
   region.center=location;

   [mapView setRegion:region animated:TRUE];
   [mapView regionThatFits:region];

I'm not sure if this is what you're after but have you tried mapView.userLocation for the CLLocation stored?

Also remember that in the iPhone Simulator the pin will always drop on Apple HQ unless (from Xcode4) you change the simulated user's location - this is a Location Services arrow-icon just above the console in Xcode. When using a device the co-ordinate should move to your GPS location, depending on coverage.

R – iPhone MkMapView lock center to userlocation

I've already described a better way for getting updates of userLocation.location property of MKMapView through KVO notifications instead of using another location manager. How do I zoom an MKMapView to the users current location without CLLocationManager?

Of course, you should make some changes to the method that receive KVO notifications. Something like that:

-(void)observeValueForKeyPath:(NSString *)keyPath  
                     ofObject:(id)object  
                       change:(NSDictionary *)change  
                      context:(void *)context {  

    if ([self.mapView isUserLocationVisible]) {  
       [self.mapView setCenterCoordinate:self.mapView.userLocation.location.coordinate
                                animated:YES];
    }
}

I've tested this code and it works fine.

Best Answer

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