title: MKCoordinateRegionMakeWithDistance does not set the correct region on the MapView
body: <p>I have this code :</p>
  
  <pre><code>- (void)viewDidLoad
  {
      [super viewDidLoad];
  
      CLLocationCoordinate2D userLocation = CLLocationCoordinate2DMake(48.9793946200, 2.4726272850);
      CLLocationDistance dist1 = 636.9887048804;
      CLLocationDistance dist2 = 900.8380655203;
      CLLocationDistance dist = dist1;
  
      [self.myMapView setRegion:MKCoordinateRegionMakeWithDistance(userLocation, dist, dist) animated:YES];
  
      // TEST
      // ------------------------------------------------------------
      MKCoordinateRegion region = self.myMapView.region;
      CLLocationDegrees lat = region.center.latitude;
      CLLocationDegrees lon = region.center.longitude - region.span.longitudeDelta/2;
      CLLocation *west = [[[CLLocation alloc] initWithLatitude:lat longitude:lon] autorelease];
  
      NSLog(@"User location: lat : %.10lf long : %.10lf", userLocation.latitude, userLocation.longitude);
      NSLog(@"distance set: %.10lfm", dist);
      NSLog(@"center: lat : %.8lf long : %.8lf", region.center.latitude, region.center.longitude);
  
      CLLocation* centerRegion = [[[CLLocation alloc] initWithLatitude:region.center.latitude longitude:region.center.longitude] autorelease];
      NSLog(@"distance to western boundary: %.2lfm", [centerRegion distanceFromLocation:west]);
  
      lat = region.center.latitude - region.span.latitudeDelta/2 ;
      lon = region.center.longitude;
      CLLocation *north = [[[CLLocation alloc] initWithLatitude:lat longitude:lon] autorelease];
  
      NSLog(@"distance to western boundary: %.2lfm", [centerRegion distanceFromLocation:north]);
      // ------------------------------------------------------------
  }
  </code></pre>
  
  <p>When setting dist = dist1, that gives :</p>
  
  <pre><code>User location: lat : 48.9793946200 long : 2.4726272850
  distance set: 636.9887048804m
  
  center: lat : 48.97937199 long : 2.47269630
  distance to western boundary: 500.44m
  distance to western boundary: 650.57m
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/JuTUl.png" alt="enter image description here"></p>
  
  <p>When setting dist = dist2, that gives :</p>
  
  <pre><code>User location: lat : 48.9793946200 long : 2.4726272850
  distance set: 900.8380655203m
  
  center: lat : 48.97937199 long : 2.47269630
  distance to western boundary: 500.44m
  distance to western boundary: 650.57m
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/8PyrV.png" alt="enter image description here"></p>
  
  <p>What's the problem here ? Why do I have the same display with 2 different distances ?</p>
  
  <p><strong>Final question : How can I be sure to display the wanted meters on the map, at minimum for horizontal and vertical visual (with or without animation of course) ?</strong></p>