MKMapView center and zoom in

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一向
一向 2021-02-19 23:16

I am using MKMapView on a project and would like to center the map on a coordinate and zoom in. Just like Google maps has:

GMSCameraPosition.camera(withLatitude:         


        
9条回答
  •  醉梦人生
    2021-02-19 23:45

    Code based on : http://troybrant.net/blog/2010/01/set-the-zoom-level-of-an-mkmapview/

        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 * M_PI / 180.0)
        }
    
        private func latitudeToPixelSpaceY(latitude: Double) -> Double {
            return round(MERCATOR_OFFSET - MERCATOR_RADIUS * log((1 + sin(latitude * M_PI / 180.0)) / (1 - sin(latitude * M_PI / 180.0))) / 2.0)
        }
    
        private  func pixelSpaceXToLongitude(pixelX: Double) -> Double {
            return ((round(pixelX) - MERCATOR_OFFSET) / MERCATOR_RADIUS) * 180.0 / M_PI;
        }
    
        private func pixelSpaceYToLatitude(pixelY: Double) -> Double {
            return (M_PI / 2.0 - 2.0 * atan(exp((round(pixelY) - MERCATOR_OFFSET) / MERCATOR_RADIUS))) * 180.0 / M_PI;
        }
    
        private func coordinateSpan(withMapView mapView: MKMapView, centerCoordinate: CLLocationCoordinate2D, zoomLevel: UInt) ->MKCoordinateSpan {
            let centerPixelX = longitudeToPixelSpaceX(centerCoordinate.longitude)
            let centerPixelY = latitudeToPixelSpaceY(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(topLeftPixelX)
            let maxLng = pixelSpaceXToLongitude(topLeftPixelX + scaledMapWidth)
            let longitudeDelta = maxLng - minLng;
    
            let minLat = pixelSpaceYToLatitude(topLeftPixelY)
            let maxLat = pixelSpaceYToLatitude(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)
    
        }
    }
    

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