Zoom MKMapView to fit polyline points

Question

I have an array, allCollections, that holds programmatically-created arrays of CLLocations the user has recorded through my iOS app. Each sub-array in allCollections holds all the location points in a trip taken.

I draw MKPolylines off of the CLLocations in the arrays in allCollections to represent those trips on an MKMapView. My question is this: With the polylines added to the map, how would I go about programmatically zooming and centering the map to display all of them?

Answer 1

-(void)zoomToPolyLine: (MKMapView*)map polyline: (MKPolyline*)polyline animated: (BOOL)animated
{
    [map setVisibleMapRect:[polyline boundingMapRect] edgePadding:UIEdgeInsetsMake(10.0, 10.0, 10.0, 10.0) animated:animated];
}

Answer 2

-(void)zoomToPolyLine: (MKMapView*)map polyLine: (MKPolyline*)polyLine 
animated (BOOL)animated
{
MKPolygon* polygon = 
    [MKPolygon polygonWithPoints:polyLine.points count:polyLine.pointCount];

[map setRegion:MKCoordinateRegionForMapRect([polygon boundingMapRect]) 
     animated:animated];
}

Answer 3

You could loop through all CLLocations recording the max/min coordinates and use that to set a view rect like they do on this question iOS MKMapView zoom to show all markers .

Or you could go through each of your overlays and get their boundingMapRect then use MKMapRectUnion (http://developer.apple.com/library/ios/documentation/MapKit/Reference/MapKitFunctionsReference/Reference/reference.html#//apple_ref/c/func/MKMapRectUnion) to combine them all until you have one MKMapRect that covers them all and use that to set the view.

[mapView setVisibleMapRect:zoomRect animated:YES]

This question shows a simple loop combining the maprects in unions as I suggested: MKMapRect zooms too much

Answer 4

in swift:

if let first = mapView.overlays.first {
    let rect = mapView.overlays.reduce(first.boundingMapRect, combine: {MKMapRectUnion($0, $1.boundingMapRect)})
    mapView.setVisibleMapRect(rect, edgePadding: UIEdgeInsets(top: 50.0, left: 50.0, bottom: 50.0, right: 50.0), animated: true)
}

this will zoom/pan to fit all overlays with a little buffer

Answer 5

Swift 3 version of garafajon excellent code

    if let first = self.mapView.overlays.first {
        let rect = self.mapView.overlays.reduce(first.boundingMapRect, {MKMapRectUnion($0, $1.boundingMapRect)})
        self.mapView.setVisibleMapRect(rect, edgePadding: UIEdgeInsets(top: 50.0, left: 50.0, bottom: 50.0, right: 50.0), animated: true)
    }

Answer 6

Swift 4 / slightly modified version of fundtimer's answer.

 func setVisibleMapArea(polyline: MKPolyline, edgeInsets: UIEdgeInsets, animated: Bool = false) {
    mapView.setVisibleMapRect(polyline.boundingMapRect, edgePadding: edgeInsets, animated: animated)
}

Calling the above using a route's polyline and leaving the default of not animated, and adding small edge insets of 10 all around:

setVisibleMapArea(polyline: route.polyline, edgeInsets: UIEdgeInsetsMake(10.0, 10.0, 10.0, 10.0))

Answer 7

@Fundtimer pointed it right way, Only thing is that Padding needs to be adjusted as per visual needs, that way it will support all the other overlays and following is the generic solution for all overlays.

-(void)zoomIntoExistingMapObjectForAnnot:(CustomMapAnnotation *)annot
{
   id overlay = annot.shape;//I have overlay property in custom annotation class.
   [_mapView setVisibleMapRect:[overlay boundingMapRect] edgePadding:UIEdgeInsetsMake(150.0, 150.0, 150.0, 150.0) animated:YES];
}

Answer 8

I have another solution for this problem

private func mapRegion() -> MKCoordinateRegion? {


    let latitudes = self.coordinates.map { location -> Double in

        return location.latitude
    }

    let longitudes = self.coordinates.map { location -> Double in

        return location.longitude
    }

    let maxLat = latitudes.max()!
    let minLat = latitudes.min()!
    let maxLong = longitudes.max()!
    let minLong = longitudes.min()!

    let center = CLLocationCoordinate2D(latitude: (minLat + maxLat) / 2,
                                        longitude: (minLong + maxLong) / 2)
    let span = MKCoordinateSpan(latitudeDelta: (maxLat - minLat) * 1.3,
                                longitudeDelta: (maxLong - minLong) * 1.3)
    return MKCoordinateRegion(center: center, span: span)
}

Where coordinates is Array of CLLocationCoordinate2D

Hope it is helpful to someone