Mapkit - Zoom level keeps resetting

Question

Hello,

I have the following code in place:

-(void)viewDidLoad 
{
    //Set Zoom level using Span
    MKCoordinateSpan span;
    span.latitudeDelta = 0.05;
    span.longitudeDelta = 0.05;
    region.span = span;
}


-(void)locationChange:(CLLocation *)newLocation: (CLLocation *)oldLocation
{
    // This zooms in on the users current loation.
    curlocation = newLocation.coordinate;
    region.center = curlocation;

    [_mapView setRegion:region animated:TRUE];
}

Initially the zoom level is set as per the code in ViewDidLoad. How do I store the zoom level id the user zooms in or out, as everytime a new location update is received the zoom level is reset.

Is there a way of detecting the user has zoomed in or out ?

UPDATE

I've add the regionDidChangeAnimated method as follows:

- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated
{
    NSLog(@"Region DID change.   Center is now %f,%f,  Deltas=%f,%f", 
          region.center.latitude, region.center.longitude,  
          region.span.latitudeDelta, region.span.longitudeDelta);
}

Output in the log looks like:

2010-11-01 15:17:29.317 Legginit[2948:307] Region DID change.
Center is now 54.181150,-8.483177, Deltas=0.050000,0.050000

2010-11-01 15:17:30.553 Legginit[2948:307] Region DID change.
Center is now 54.181150,-8.483177, Deltas=0.050000,0.050000

2010-11-01 15:17:31.063 Legginit[2948:307] Region DID change.
Center is now 54.181150,-8.483177, Deltas=0.050000,0.050000

2010-11-01 15:17:31.653 Legginit[2948:307] Region DID change.
Center is now 54.181150,-8.483177, Deltas=0.050000,0.050000

2010-11-01 15:17:32.582 Legginit[2948:307] Region DID change.
Center is now 54.181150,-8.483177, Deltas=0.050000,0.050000

2010-11-01 15:17:33.608 Legginit[2948:307] Region DID change.
Center is now 54.181150,-8.483177, Deltas=0.050000,0.050000

As I zoom in on the phone I was expecting the Delta Values to change but they remain at 0.05. Am I misunderstanding how this works. I thought I could capture the Delta values and store them so I could reset the zoom level if the user exits and re-enters the map.

Regards, Stephen

Answer 1

In locationChange, try updating your region's span to the _mapView's current span before calling setRegion:

region.span = _mapView.region.span;

If you really need to detect zoom changes as they happen, implement the MKMapViewDelegate method regionWillChangeAnimated or regionDidChangeAnimated.

Edit:
You need to get the new region from the mapView and set your region instance variable to it (the map view won't set your instance variable automatically):

- (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated
{
    region = mapView.region;  //<-- add this

    NSLog(@"Region DID change.   Center is now %f,%f,  Deltas=%f,%f",
          region.center.latitude, region.center.longitude,  
          region.span.latitudeDelta, region.span.longitudeDelta);
}