MapKit: How can I pan and zoom to fit all my annotations? - iphone

Question

So I've got a bunch of annotations spread out on my map... everything is just dandy. Now I need to be able to set the map's position and zoom so they all fit perfectly. How can I do this?

Answer 1

From Apple forums...
- (void)recenterMap {
NSArray *coordinates = [self.mapView valueForKeyPath:#"annotations.coordinate"];
CLLocationCoordinate2D maxCoord = {-90.0f, -180.0f};
CLLocationCoordinate2D minCoord = {90.0f, 180.0f};
for(NSValue *value in coordinates) {
CLLocationCoordinate2D coord = {0.0f, 0.0f};
[value getValue:&coord];
if(coord.longitude > maxCoord.longitude) {
maxCoord.longitude = coord.longitude;
}
if(coord.latitude > maxCoord.latitude) {
maxCoord.latitude = coord.latitude;
}
if(coord.longitude < minCoord.longitude) {
minCoord.longitude = coord.longitude;
}
if(coord.latitude < minCoord.latitude) {
minCoord.latitude = coord.latitude;
}
}
MKCoordinateRegion region = {{0.0f, 0.0f}, {0.0f, 0.0f}};
region.center.longitude = (minCoord.longitude + maxCoord.longitude) / 2.0;
region.center.latitude = (minCoord.latitude + maxCoord.latitude) / 2.0;
region.span.longitudeDelta = maxCoord.longitude - minCoord.longitude;
region.span.latitudeDelta = maxCoord.latitude - minCoord.latitude;
[self.mapView setRegion:region animated:YES];
}

Answer 2

#interface MKMapView (zoomToFit)
- (void)zoomToFitOverlays; //Animation defaults to YES
- (void)zoomToFitOverlay:(id<MKOverlay>)anOverlay;
- (void)zoomToFitOverlays:(NSArray *)someOverlays;
- (void)zoomToFitOverlaysAnimated:(BOOL)animated;
- (void)zoomToFitOverlay:(id<MKOverlay>)anOverlay animated:(BOOL)animated;
- (void)zoomToFitOverlays:(NSArray *)someOverlays animated:(BOOL)animated;
- (void)zoomToFitOverlays:(NSArray *)someOverlays animated:(BOOL)animated insetProportion:(CGFloat)insetProportion; //inset 0->1, defaults in other methods to .1 (10%)
#end
#implementation MKMapView (zoomToFit)
#pragma mark -
#pragma mark Zoom to Fit
- (void)zoomToFitOverlays {
[self zoomToFitOverlaysAnimated:YES];
}
- (void)zoomToFitOverlay:(id<MKOverlay>)anOverlay {
[self zoomToFitOverlay:[NSArray arrayWithObject:anOverlay] animated:YES];
}
- (void)zoomToFitOverlays:(NSArray *)someOverlays {
[self zoomToFitOverlays:someOverlays animated:YES];
}
- (void)zoomToFitOverlaysAnimated:(BOOL)animated {
[self zoomToFitOverlays:self.overlays animated:animated];
}
- (void)zoomToFitOverlay:(id<MKOverlay>)anOverlay animated:(BOOL)animated {
[self zoomToFitOverlays:[NSArray arrayWithObject:anOverlay] animated:YES];
}
- (void)zoomToFitOverlays:(NSArray *)someOverlays animated:(BOOL)animated {
[self zoomToFitOverlays:someOverlays animated:animated insetProportion:.1];
}
- (void)zoomToFitOverlays:(NSArray *)someOverlays animated:(BOOL)animated insetProportion:(CGFloat)insetProportion {
//Check
if ( !someOverlays || !someOverlays.count ) {
return;
}
//Union
MKMapRect mapRect = MKMapRectNull;
if ( someOverlays.count == 1 ) {
mapRect = ((id<MKOverlay>)someOverlays.lastObject).boundingMapRect;
} else {
for ( id<MKOverlay> anOverlay in someOverlays ) {
mapRect = MKMapRectUnion(mapRect, anOverlay.boundingMapRect);
}
}
//Inset
CGFloat inset = (CGFloat)(mapRect.size.width*insetProportion);
mapRect = [self mapRectThatFits:MKMapRectInset(mapRect, inset, inset)];
//Set
MKCoordinateRegion region = MKCoordinateRegionForMapRect(mapRect);
[self setRegion:region animated:animated];
}
#end