Zooms out a MKMapView to enclose all its annotations (inc. current location)

iOSMapKitFitAnnotations.m

MKMapRect zoomRect = MKMapRectNull;
for (id <MKAnnotation> annotation in mapView.annotations) {
    MKMapPoint annotationPoint = MKMapPointForCoordinate(annotation.coordinate);
    MKMapRect pointRect = MKMapRectMake(annotationPoint.x, annotationPoint.y, 0, 0);
    if (MKMapRectIsNull(zoomRect)) {
        zoomRect = pointRect;
    } else {
        zoomRect = MKMapRectUnion(zoomRect, pointRect);
    }
}
[mapView setVisibleMapRect:zoomRect animated:YES];

What if you had multiple annotations but you only ever wanted to zoom out to the closest one to your current location?

All gists which are showed above, cannot include current location.
I just added some changes to @Souf-R's function
This version can include device's current location:

func fitMapViewToAnnotaionList(annotations: [MKPointAnnotation], userLocation: CLLocationCoordinate2D) -> Void {
        let mapEdgePadding = UIEdgeInsets(top: 20, left: 20, bottom: 20, right: 20)
        var zoomRect:MKMapRect = MKMapRectNull

        for index in 0..<annotations.count {
            let annotation = annotations[index]
            let aPoint:MKMapPoint = MKMapPointForCoordinate(annotation.coordinate)
            let rect:MKMapRect = MKMapRectMake(aPoint.x, aPoint.y, 0.1, 0.1)

            if MKMapRectIsNull(zoomRect) {
                zoomRect = rect
            } else {
                zoomRect = MKMapRectUnion(zoomRect, rect)
            }
        }

        let aPoint:MKMapPoint = MKMapPointForCoordinate(userLocation)
        let rect:MKMapRect = MKMapRectMake(aPoint.x, aPoint.y, 0.1, 0.1)

        if MKMapRectIsNull(zoomRect) {
            zoomRect = rect
        } else {
            zoomRect = MKMapRectUnion(zoomRect, rect)
        }
        mapView.setVisibleMapRect(zoomRect, edgePadding: mapEdgePadding, animated: true)
    }

Thanks

perfect solution!

Great solution!!! Thanks!! Here is the swift version of the code with padding set -

        var zoomRect = MKMapRectNull
        for annotation in mkMapView.annotations {
            let annotationPoint = MKMapPointForCoordinate(annotation.coordinate)
            let pointRect = MKMapRectMake(annotationPoint.x, annotationPoint.y, 0, 0)
            if (MKMapRectIsNull(zoomRect)) {
                zoomRect = pointRect
            } else {
                zoomRect = MKMapRectUnion(zoomRect, pointRect)
            }
        }
        mkMapView.setVisibleMapRect(zoomRect, edgePadding: UIEdgeInsetsMake(40, 40, 40, 40), animated: true)

Nice solution! Thanks

nice solutions

Thanks for sharing ,Saved my time :)
👍

Thanks for the Solution, works perfekt.

I needed to run

mkMapView.layoutIfNeeded()

before
mkMapView.setVisibleMapRect(zoomRect, edgePadding: UIEdgeInsetsMake(40, 40, 40, 40), animated: true)

if i did not run layoutIfNeeded() the EdgeInset is not set in ViewDidLoad or ViewDidApear
or the zoom is a bit to large.

Even easier:

static func fittingMapRect(forCoordinates coordinates: [CLLocationCoordinate2D]) -> MKMapRect {

    guard !coordinates.isEmpty else {
        return MKMapRectNull
    }
    let mapPoints = coordinates.map { MKMapPointForCoordinate($0) }
    let mapRects = mapPoints.map { MKMapRect(origin: $0, size: MKMapSize(width: 1, height: 1)) }
    let fittingRect = mapRects.reduce(MKMapRectNull, MKMapRectUnion)
    return fittingRect
}

Unfortunately, showAnnotations is too zoomed out and doesn't look good. Thanks for this code everyone, here's my condensed version:

mapView.setVisibleMapRect(
    mapView.annotations.reduce(MKMapRectNull) { result, next in
        let point = MKMapPointForCoordinate(next.coordinate)
        let rect = MKMapRectMake(point.x, point.y, 0, 0)
        guard !MKMapRectIsNull(result) else { return rect }
        return MKMapRectUnion(result, rect)
    },
    edgePadding: UIEdgeInsetsMake(20, 20, 40, 20),
    animated: true
)

 extension MKMapView {

    var MERCATOR_OFFSET : Double {
        return 268435456.0
    }

    var MERCATOR_RADIUS : Double  {
        return 85445659.44705395
    }

    private func longitudeToPixelSpaceX(longitude: Double) -> Double {
        return round(MERCATOR_OFFSET + MERCATOR_RADIUS * longitude * Double.pi / 180.0)
    }

    private func latitudeToPixelSpaceY(latitude: Double) -> Double {
        return round(MERCATOR_OFFSET - MERCATOR_RADIUS * log((1 + sin(latitude * Double.pi / 180.0)) / (1 - sin(latitude * Double.pi / 180.0))) / 2.0)
    }

    private  func pixelSpaceXToLongitude(pixelX: Double) -> Double {
        return ((round(pixelX) - MERCATOR_OFFSET) / MERCATOR_RADIUS) * 180.0 / Double.pi;
    }

    private func pixelSpaceYToLatitude(pixelY: Double) -> Double {
        return (Double.pi / 2.0 - 2.0 * atan(exp((round(pixelY) - MERCATOR_OFFSET) / MERCATOR_RADIUS))) * 180.0 / Double.pi;
    }

    private func coordinateSpan(withMapView mapView: MKMapView, centerCoordinate: CLLocationCoordinate2D, zoomLevel: UInt) ->MKCoordinateSpan {
        let centerPixelX = longitudeToPixelSpaceX(longitude: centerCoordinate.longitude)
        let centerPixelY = latitudeToPixelSpaceY(latitude: centerCoordinate.latitude)

        let zoomExponent = Double(20 - zoomLevel)
        let zoomScale = pow(2.0, zoomExponent)

        let mapSizeInPixels = mapView.bounds.size
        let scaledMapWidth =  Double(mapSizeInPixels.width) * zoomScale
        let scaledMapHeight = Double(mapSizeInPixels.height) * zoomScale

        let topLeftPixelX = centerPixelX - (scaledMapWidth / 2);
        let topLeftPixelY = centerPixelY - (scaledMapHeight / 2);

        // find delta between left and right longitudes
        let minLng = pixelSpaceXToLongitude(pixelX: topLeftPixelX)
        let maxLng = pixelSpaceXToLongitude(pixelX: topLeftPixelX + scaledMapWidth)
        let longitudeDelta = maxLng - minLng;

        let minLat = pixelSpaceYToLatitude(pixelY: topLeftPixelY)
        let maxLat = pixelSpaceYToLatitude(pixelY: topLeftPixelY + scaledMapHeight)
        let latitudeDelta = -1 * (maxLat - minLat);

        let span = MKCoordinateSpanMake(latitudeDelta, longitudeDelta)
        return span
    }

    func zoom(toCenterCoordinate centerCoordinate:CLLocationCoordinate2D ,zoomLevel: UInt) {
        let zoomLevel = min(zoomLevel, 20)
        let span = self.coordinateSpan(withMapView: self, centerCoordinate: centerCoordinate, zoomLevel: zoomLevel)
        let region = MKCoordinateRegionMake(centerCoordinate, span)
        self.setRegion(region, animated: true)

    }
}

Original Code Credit: http://troybrant.net/blog/2010/01/set-the-zoom-level-of-an-mkmapview/
Swift 2.3 Translation Credit: https://stackoverflow.com/users/2729171/apinho
Swift 4.x Swift Translation: By me. 👍

This is the easiest way:

map.layoutMargins = UIEdgeInsets(top: 10, right: 10, bottom: 10, left: 10)
map.showAnnotations(map.annotations, animated: true)

It works! I promise.

Thanks for this!
In my particular case, I had annotations and overlays for them, like the user's location blue circle overlay (userLocation.horizontalAccuracy). To fit all the annotations and their overlays, I modified this a bit and got these two extensions.

extension MKMapView {
    func setVisibleMapRectToFitAllAnnotations(animated: Bool = true,
                                              shouldIncludeUserAccuracyRange: Bool = true,
                                              edgePadding: UIEdgeInsets = UIEdgeInsets(top: 35, left: 35, bottom: 35, right: 35)) {
        var mapOverlays = overlays

        if shouldIncludeUserAccuracyRange, let userLocation = userLocation.location {
            let userAccuracyRangeCircle = MKCircle(center: userLocation.coordinate, radius: userLocation.horizontalAccuracy)
            mapOverlays.append(MKOverlayRenderer(overlay: userAccuracyRangeCircle).overlay)
        }

        let zoomRect = MKMapRect(bounding: mapOverlays)
        setVisibleMapRect(zoomRect, edgePadding: edgePadding, animated: animated)
    }
} 

extension MKMapRect {
 init(bounding overlays: [MKOverlay]) {
        self = .null
        overlays.forEach { overlay in
            let rect: MKMapRect = overlay.boundingMapRect
            self = self.union(rect)
        }
    }
}

I just modified SimonJanevski's answer to show all annotations and overlays present on MapView.

extension MKMapView {
  func setVisibleMapRectToFitAllAnnotations(animated: Bool = true,
                                            shouldIncludeUserAccuracyRange: Bool = true,
                                            shouldIncludeOverlays: Bool = true,
                                            edgePadding: UIEdgeInsets = UIEdgeInsets(top: 35, left: 35, bottom: 35, right: 35)) {
    var mapOverlays = overlays
    
    if shouldIncludeUserAccuracyRange, let userLocation = userLocation.location {
      let userAccuracyRangeCircle = MKCircle(center: userLocation.coordinate, radius: userLocation.horizontalAccuracy)
      mapOverlays.append(MKOverlayRenderer(overlay: userAccuracyRangeCircle).overlay)
    }
    
    if shouldIncludeOverlays {
      let annotations = self.annotations.filter { !($0 is MKUserLocation) }
      annotations.forEach { annotation in
        let cirlce = MKCircle(center: annotation.coordinate, radius: 1)
        mapOverlays.append(cirlce)
      }
    }
    
    let zoomRect = MKMapRect(bounding: mapOverlays)
    setVisibleMapRect(zoomRect, edgePadding: edgePadding, animated: animated)
  }
}

extension MKMapRect {
  init(bounding overlays: [MKOverlay]) {
    self = .null
    overlays.forEach { overlay in
      let rect: MKMapRect = overlay.boundingMapRect
      self = self.union(rect)
    }
  }
}