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copied!<p>Its not radius what is required.</p> <p>You need to use the region parameter from mapView. </p> <p>Check out apple docs, it is pretty much clear from those.</p> <p>Go thru this tutorial. It will help you a lot</p> <p><a href="http://www.icodeblog.com/2009/12/21/introduction-to-mapkit-in-iphone-os-3-0/" rel="nofollow">icode blog mapkit demo</a></p> <p>specifically you need to set something like this..</p> <pre><code>MKCoordinateSpan span = [self coordinateSpanWithMapView:self centerCoordinate:centerCoordinate andZoomLevel:zoomLevel]; MKCoordinateRegion region = MKCoordinateRegionMake(centerCoordinate, span); [self setRegion:region animated:animated]; </code></pre> <p>where span can be calculated as</p> <pre><code>- (MKCoordinateSpan)coordinateSpanWithMapView:(MKMapView *)mapView centerCoordinate:(CLLocationCoordinate2D)centerCoordinate andZoomLevel:(NSUInteger)zoomLevel { // convert center coordiate to pixel space double centerPixelX = [self longitudeToPixelSpaceX:centerCoordinate.longitude]; double centerPixelY = [self latitudeToPixelSpaceY:centerCoordinate.latitude]; // determine the scale value from the zoom level NSInteger zoomExponent = 20 - zoomLevel; double zoomScale = pow(2, zoomExponent); // scale the map’s size in pixel space CGSize mapSizeInPixels = mapView.bounds.size; double scaledMapWidth = mapSizeInPixels.width * zoomScale; double scaledMapHeight = mapSizeInPixels.height * zoomScale; // figure out the position of the top-left pixel double topLeftPixelX = centerPixelX - (scaledMapWidth / 2); double topLeftPixelY = centerPixelY - (scaledMapHeight / 2); // find delta between left and right longitudes CLLocationDegrees minLng = [self pixelSpaceXToLongitude:topLeftPixelX]; CLLocationDegrees maxLng = [self pixelSpaceXToLongitude:topLeftPixelX + scaledMapWidth]; CLLocationDegrees longitudeDelta = maxLng - minLng; // find delta between top and bottom latitudes CLLocationDegrees minLat = [self pixelSpaceYToLatitude:topLeftPixelY]; CLLocationDegrees maxLat = [self pixelSpaceYToLatitude:topLeftPixelY + scaledMapHeight]; CLLocationDegrees latitudeDelta = -1 * (maxLat - minLat); // create and return the lat/lng span MKCoordinateSpan span = MKCoordinateSpanMake(latitudeDelta, longitudeDelta); return span; } </code></pre> <p>Cheers :)</p>

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