I draw a circle on an MKMapView. But how do I calculate the radius of this circle such that it equals the value of the radius used to draw the circle in the first place?
func setArea(_ center:CLLocationCoordinate2D, radius:CLLocationDistance) {
let area = MKCircle(center:center, radius:radius / LocationViewController.kRadiusInset)
mapView.setVisibleMapRect(mapView.mapRectThatFits(area.boundingMapRect), animated:false)
}
I've tried the following but it returns a value very slightly larger than radius passed to setArea. It calculates the distance from the center of the map to the left-hand edge.
// getRadius
let distance = middle.distance(from: edge)
let middle = CLLocation(latitude: mapView.region.center.latitude, longitude: mapView.region.center.longitude)
let edge = CLLocation(latitude: mapView.region.center.latitude, longitude: mapView.centerCoordinate.longitude - (mapView.region.span.longitudeDelta * 0.5))
let distance = middle.distance(from: edge)
If I pass in '4000' metres to setArea() and then afterwards calculate the map's radius (say, within mapViewDidFinishRenderingMap() I get 4010.61219348448
Why the discrepancy?
I replaced the use of a MKCircle with the following:
let region = MKCoordinateRegionMakeWithDistance(center, radius * 2, radius * 2)
mapView.region = region
This is less inaccurate. With radius == 4000 fed into this I get 4000.00048143541 after I set my MKMapView's region. This difference will creep into the user-interface but not nearly as quickly as my first approach.
Can anyone get closer?
Related
I am using a map with some annotations, I want to group the nearest annotations in annotation group to not overlap in the design in case of user zoom out, but my problem is to how to know the distance between annotations and this distance should change when zooming in and out.
the distance should be between points with x and y formate note meters
So my question is to how to catch the difference between 2 points on the map and consider the zoom
// convert location to cLLocation
let cLLocation1 = CLLocation(latitude: post1Location?.lat ?? 0, longitude: post1Location?.lng ?? 0)
let cLLocation2 = CLLocation(latitude: post2Location?.lat ?? 0, longitude: post2Location?.lng ?? 0)
// this is return the dinsactence in metres but i don't need that
let distance = cLLocation1.distance(from: cLLocation2)
let annotaionPoint1 = MKMapPoint(cLLocation1.coordinate)
let annotaionPoint2 = MKMapPoint(cLLocation2.coordinate)
let xDistance = max(annotaionPoint1.x, annotaionPoint2.x) - min(annotaionPoint1.x, annotaionPoint2.x)
let yDistance = max(annotaionPoint1.y, annotaionPoint2.y) - min(annotaionPoint1.y, annotaionPoint2.y)
this is working but zoom in and zoom out no effect so I need zoom to make change
if min(xDistance, yDistance) <= 32 {
/// action
}
While driving I record the different coordinates during the drive. If I drive between two points that is generally in a straight line, then the map span of the following code works well but if I drive around the block then the map span doesn't show the route. I can generally see that since I am using the first and last coordinate this would be why. The region is then put into a snapshot to generate an image of the map. What I'm struggling with is being able to use all coordinates to calculate the needed span.
//calculate region
let span = MKCoordinateSpan.init(latitudeDelta: fabs(startCoord.latitude - endCoord.latitude) * 1.6, longitudeDelta: fabs(endCoord.longitude - startCoord.longitude) * 1.6)
let resd = CLLocationCoordinate2D.init(latitude: startCoord.latitude - (startCoord.latitude - endCoord.latitude) * 0.5, longitude: startCoord.longitude + (endCoord.longitude - startCoord.longitude) * 0.5)
let options = MKMapSnapshotter.Options()
options.scale = UIScreen.main.scale
options.region = MKCoordinateRegion.init(center: resd, span: span);
options.size = CGSize(width: 600, height: 450) //map size
options.showsBuildings = true
options.showsPointsOfInterest = true
I found this bit of code on another question
func regionFor(coordinates coords: [CLLocationCoordinate2D]) -> MKCoordinateRegion {
var r = MKMapRect.null
for i in 0 ..< coords.count {
let p = MKMapPoint(coords[i])
r = r.union(MKMapRect(x: p.x, y: p.y, width: 0, height: 0))
}
return MKCoordinateRegion(r)
}
But I couldn't get it to work to show the circle either. Anyone have an idea of how I could do this?
A region span is a rectangle. Finding a bounding rectangle is a simpler problem than finding a circle that fully encloses a set of points.
Just set up max and min latitude and longitude variables that start with values that are out of range in the opposite direction, loop through your points, and when a points co-ord is >max or <min, replace that value. When you're done, use the min-max latitude and min-max longitude values to define your region span.
I want to get the coordinates of the corners of the rectangle. Or to find the coordinate of the north-westest most point, 50 km from the map centre.
Does anyone know how I can do that?
The point is when I move around the map, I want to always have a rectangle(the rectangle does not need to drew, I just need its coordinates for a backend request), with it's corners always at 50 km from the current centre of the map.
I'm thinking of using somehow the distance function from CLLocation, but in this case I have the distance, but not one of the coordinates.
50km = mapCenterLocation.distance(from: coordinatesUnknown)
Not really sure what do you mean, but maybe this can help
func getNewTargetCoordinate(position: CLLocationCoordinate2D, userBearing: Float, distance: Float)-> CLLocationCoordinate2D{
//haversine formula
//r is earth radius
let r = 6378140.0
let latitude1 = position.latitude * (Double.pi/180);
let longitude1 = position.longitude * (Double.pi/180);
//bearing for user heading in degree
let brng = Double(userBearing) * (Double.pi/180);
//calculating user new position based on user distance and bearing can be seen at haversine formula
var latitude2 = asin(sin(latitude1)*cos(Double(distance)/r) + cos(latitude1)*sin(Double(distance)/r)*cos(brng));
var longitude2 = longitude1 + atan2(sin(brng)*sin(Double(distance)/r)*cos(latitude1),cos(Double(distance)/r)-sin(latitude1)*sin(latitude2));
//converting latitude as degree
latitude2 = latitude2 * (180/Double.pi)
longitude2 = longitude2 * (180/Double.pi)
// return location of user
return CLLocationCoordinate2DMake(latitude2, longitude2)
}
This work for NE direction and distance in meters
for the north-west direction, I think you can just put 135 for the degree and 5000 for distance.
For the position, you need to put map center location.
edit:
For custom rectangle., you can first check for the diagonal degree
func getDiagonalDegree(x: Float, y:Float) -> Float{
return atan2(y,x)*(180/Double.pi)
}
So now you can get that returned diagonal degree to and put it in getNewTargetCoordinate. New bearing is 270+diagonalDegree.
Not sure if I understand you correctly, but I think this could help, or at least point you on some direction
CLLocationCoordinate2D northWest;
northWest = [mapView convertPoint:CGPointMake(0, 0) toCoordinateFromView:mapView];
With this you will get the coordinates for the top left corner of the map, I think you just need to adjust this to set a point 50 km of your center and get the coordinate with this same logic.
I need to draw lines to demonstrate transportation of goods on apple maps. To clarify start- and end-point, I draw a little arrowhead on the destination side.The arrowhead is drawn separately but it is reversed in one case.
>-->-->-->-
instead of
<--<--<--<-
I am using MKMapView and MKPolyline to draw lines. I am using MKOverlay to add direction arrows. The steps I follow are,
calculate bearing of
Source : CLLocationCoordinate2D(latitude: -33.8392932, longitude: 151.21519799999999)
Destination: CLLocationCoordinate2D(latitude: 39.645516999999998, longitude: -104.598724)
using the following function
open static func getDirectionOf( _ supplyLineWithCoordinates: [CLLocationCoordinate2D]) -> CGFloat {
guard let sourceCoordniate = supplyLineWithCoordinates.first,
let destinationCoordniate = supplyLineWithCoordinates.last else {
fatalError("Coordinates of supply line not found")
}
let sourcePoint: MKMapPoint = MKMapPointForCoordinate(sourceCoordniate)
let destinationPoint: MKMapPoint = MKMapPointForCoordinate(destinationCoordniate)
let x: Double = destinationPoint.x - sourcePoint.x
let y: Double = destinationPoint.y - sourcePoint.y
var arrowDirection = CGFloat(fmod(atan2(y, x), 360.0))
if arrowDirection < 0.0 {
arrowDirection += 2 * .pi
}
return arrowDirection
}
Rotate the arrow image and add it as the map overlay. The directions are calculated correctly in most of the cases, however, when I select the line shown below the direction is displayed 180 opposite. It starts from Sydney, Australia and ends in Denver, US
When trying to display the region with this two locations in mapView.setVisibleMapRect these region is not displayed, mapview tries to display region starting from Sydney (Australia) to Denver(US) through Asia and Europe, while it should display the map area I have attached above. If you have suggestions for optimisation, feel free to mention it.
I think this might be the reason, the direction should be calculated along the red line but it being calculated along the green line. Both lines are drawn by connecting same location coordinates in map. Any known workaround for this?
I solved it in a dirty way by converting coordinate to CGPoint and then calculating bearing between Points.
let destinationPoint = mapView.convert(destination, toPointTo: nil)
let sourcePoint = mapView.convert(source, toPointTo: nil)
let bearing = atan2(sourcePoint.y - destinationPoint.y, sourcePoint.x - destinationPoint.x) - .pi
Caution: This calculation will go wrong when map is rotated
I am in a confusion, on how to get a zoom level and radius of a visible area of the map (using mapkit mapview).
Here is what I am looking for (either of them or both, as needed) -
Zoom level, is to see at what level of the map is being shown to the users and with that information, I want to display the custom pins in the visible area. If zoom level is high, I need to show the actual logos of some commerce stores as pins. If zoom level is low, I need to show colored dots instead of logos.
As of now, I am using let updatedRadius = (mapView.camera.altitude)/1000 to get altitude of the camera, and if the updatedRadius value is > 25.0, I am showing colored dots. Below 25.0, I show the logos. I am doing this in regionDidChanged
Is this approach correct?
Radius, is to send it as a parameter to my REST API to fetch the list of places within that radius. When user zooms out on the map, visible area increases and so the REST API needs bigger radius to return the places covered in that area.
Ultimately, what should happen is, whenever user zooms out, then the radius changes. I need to send this changed radius to my REST to get an updated list.
What are latitude longtitude deltas, can we get radius/width of visible area using these values?
let latitudeDeltaVal = mapView.region.span.latitudeDelta
let longitudeDeltaVal = mapView.region.span.longitudeDelta
Can someone throw some light on what needs to be done please?
Since you need to call the api when the region changes you need to calculate the radius in mapView's delegate function, RegionDidChange.
func mapView(mapView: MKMapView, regionDidChangeAnimated animated: Bool) {
let centralLocation = CLLocation(latitude: mapView.centerCoordinate.latitude, longitude: mapView.centerCoordinate.longitude)
self.centralLocationCoordinate = mapView.centerCoordinate
print("Radius - \(self.getRadius(centralLocation))")
}
func getRadius(centralLocation: CLLocation) -> Double{
let topCentralLat:Double = centralLocation.coordinate.latitude - mapView.region.span.latitudeDelta/2
let topCentralLocation = CLLocation(latitude: topCentralLat, longitude: centralLocation.coordinate.longitude)
let radius = centralLocation.distanceFromLocation(topCentralLocation)
return radius / 1000.0 // to convert radius to meters
}
To account for both landscape and portrait orientations, and/or situations where the map orientation is close to Northeast, Northwest, Southwest, Southeast, and to enclose the full screen up to the corners, one should consider both latitudeDelta and longitudeDelta:
func getRadius() -> Double{
let centralLocation = CLLocation(latitude: mapView.region.center.latitude, longitude: mapView.region.center.longitude)
let cornerOfMap = CLLocation(latitude: centralLocation.coordinate.latitude + mapView.region.span.latitudeDelta , longitude: centralLocation.coordinate.longitude + mapView.region.span.longitudeDelta)
let radius = centralLocation.distance(from: cornerOfMap)
return radius / 1000.0 // to convert radius to meters
}