How to move MKMapView based on selected annotation

Question

I have an MKMapView which populates the entirety of my view, but when a pin is selected, I am sliding up another view on top of the map. I want to move the map so the pin will appear in the centre of the visible area of the map.

Difficult to explain but hopefully it makes sense! Thanks in advance.

Counterpunch

Answer 1

You could try getting the MKMapRect from visibleMapRect for the map view, converting the annotation's coordinate to an MKMapPoint, resetting the MKMapRect's origin so the MKMapPoint is in the appropriate position, and then using setVisibleMapRect:animated: to set the visible region to the new MKMapRect.

For example, if you wanted to move the map so the annotation is centered horizontally and 25% of the way down vertically, you could do something like this:

MKMapRect r = [mapView visibleMapRect];
MKMapPoint pt = MKMapPointForCoordinate([annotation coordinate]);
r.origin.x = pt.x - r.size.width * 0.5;
r.origin.y = pt.y - r.size.height * 0.25;
[mapView setVisibleMapRect:r animated:YES]; 

Disarray

Answer 2

Using MKMapViewDelegate method:

func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {

    // center the mapView on the selected pin
    let region = MKCoordinateRegion(center: view.annotation!.coordinate, span: mapView.region.span)
    mapView.setRegion(region, animated: true)
}

Jason

Answer 3

I built it on Swift 4, based on answers here

func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {

        // center the mapView on the selected pin
        var dest = view.annotation!.coordinate
        if view.annotation?.title == "Name of Annotation View"{//This is for move a little down depending on the MKAnnotationView size
            dest.latitude = dest.latitude + 0.002
        }
        let span = MKCoordinateSpan.init(latitudeDelta: 0.01, longitudeDelta: 0.01)
        let region = MKCoordinateRegion(center: dest, span: span)
        mapView.setRegion(region, animated: true)


    }

Nettlesome

Answer 4

I ended up with following procedures:

** Centering on annotation:**

- (void) centerOnSelection:(id<MKAnnotation>)annotation
{
    MKCoordinateRegion region = self.mapView.region;
    region.center = annotation.coordinate;

    CGFloat per = ([self sizeOfBottom] - [self sizeOfTop]) / (2 * self.mapView.frame.size.height);
    region.center.latitude -= self.mapView.region.span.latitudeDelta * per;

    [self.mapView setRegion:region animated:YES];
}

** Zooming on annotation:**

- (void) zoomAndCenterOnSelection:(id<MKAnnotation>)annotation
{
    DLog(@"zoomAndCenterOnSelection");

    MKCoordinateRegion region = self.mapView.region;
    MKCoordinateSpan span = MKCoordinateSpanMake(0.005, 0.005);

    region.center = annotation.coordinate;

    CGFloat per = ([self sizeOfBottom] - [self sizeOfTop]) / (2 * self.mapView.frame.size.height);
    region.center.latitude -= self.mapView.region.span.latitudeDelta * span.latitudeDelta / region.span.latitudeDelta * per;

    region.span = span;

    [self.mapView setRegion:region animated:YES];
}

-(CGFloat) sizeOfBottom and -(CGFloat) sizeOfTop both return height of panels covering the mapview from the layout guides

Apoplectic