Zooming MKMapView to fit annotation pins?

This is the one I found here that worked for me:

(EDIT: I have updated the solution using @Micah's suggestion to increase the pointRect by 0.1 to ensure the rect doesn't end up being infinitesimally small!)

MKMapRect zoomRect = MKMapRectNull;for (id <MKAnnotation> annotation in mapView.annotations){    MKMapPoint annotationPoint = MKMapPointForCoordinate(annotation.coordinate);    MKMapRect pointRect = MKMapRectMake(annotationPoint.x, annotationPoint.y, 0.1, 0.1);    zoomRect = MKMapRectUnion(zoomRect, pointRect);}[mapView setVisibleMapRect:zoomRect animated:YES];

You could also update this to include the userLocation pin by replacing the first line with:

MKMapPoint annotationPoint = MKMapPointForCoordinate(mapView.userLocation.coordinate);MKMapRect zoomRect = MKMapRectMake(annotationPoint.x, annotationPoint.y, 0.1, 0.1);

You've got it right.

Find your maximum and minimum latitudes and longitudes, apply some simple arithmetic, and use MKCoordinateRegionMake.

For iOS 7 and above, use showAnnotations:animated:, from MKMapView.h:

// Position the map such that the provided array of annotations are all visible to the fullest extent possible. - (void)showAnnotations:(NSArray *)annotations animated:(BOOL)animated NS_AVAILABLE(10_9, 7_0);

Apple has added a new method for IOS 7 to simplify life a bit.

[mapView showAnnotations:yourAnnotationArray animated:YES];

You can easily pull from an array stored in the map view:

yourAnnotationArray = mapView.annotations;

and quickly adjust the camera too!

mapView.camera.altitude *= 1.4;

this won't work unless the user has iOS 7+ or OS X 10.9+ installed. check out custom animation here