What's the best way to zoom out and fit all annotations in MapKit

Question

Quick background of what I have going on. UIMapView loads and shows a single annotation (Never more than one). On the menu bar, there is a Locate Me button, on tap the use

Answer 1

You can use this code to show all annotations

MKMapRect zoomRect = MKMapRectNull;
for (id  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];

if you want to include user location just replace two lines below with the first line of above code

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