Monotouch – Draw a MKPolyline on Map

mkmapviewxamarin.ios

I've a MKPolyline made of CLLocationCoordinate2D array (Points). That's all fine.

I added this line to the Map as an overlay, like so: Map.AddOverlay(line);

I event set this: Map.SetVisibleMapRect(line.BoundingMapRect, true);

But the line does not show up although the Map bounds are correct.

I'm looking into MKPolylineView, but can't get it to work.

Anyone knows to set colour and line width?

Thanks

Best Answer

After much head scratching, here is how to display a MKPolyline on a MKMapView:

Step 1: Create a delegate method for Map GetViewForOverlay

Map.GetViewForOverlay = Map_GetViewForOverlay;

Where Map is the MKMapView.

MKOverlayView Map_GetViewForOverlay(MKMapView mapView, NSObject overlay)
{
    if(overlay.GetType() == typeof(MKPolyline))
    {
       MKPolylineView p = new MKPolylineView((MKPolyline)overlay);
       p.LineWidth = 2.0f;
       p.StrokeColor = UIColor.Green;
       return p;
    }
    else
        return null;
}

Step 2: Create a new instance of MKPolyline

MKPolyline line = MKPolyline.FromCoordinates(polyPoints);

Where polyPoints is an Array of CLLocationCoordinate2D.

Step 3: Add the overlay to the map

Map.AddOverlay(line);

Step 4: Use code below to zoom and change Map bounds to fit route

Map.SetVisibleMapRect(line.BoundingMapRect, true);

Related Solutions

Ios – How to draw a MKPolyline on a MapView

Done.

Was a very stupid thing, i didn't set the delegate for the MapView. Simply adding [map setDelegate:self]; did the trick.

Thank you anyway!.

Ios – latitude and longitude points from MKPolyline

To get coordinates of the polyline from an MKRoute, use the getCoordinates:range: method.
That method is in the MKMultiPoint class which MKPolyline inherits from.

That also means this works for any polyline -- whether it was created by you or by MKDirections.

You allocate a C array big enough to hold the number of coordinates you want and specify the range (eg. all points starting from the 0th).

Example:

//route is the MKRoute in this example
//but the polyline can be any MKPolyline

NSUInteger pointCount = route.polyline.pointCount;

//allocate a C array to hold this many points/coordinates...
CLLocationCoordinate2D *routeCoordinates 
    = malloc(pointCount * sizeof(CLLocationCoordinate2D));

//get the coordinates (all of them)...
[route.polyline getCoordinates:routeCoordinates 
                         range:NSMakeRange(0, pointCount)];

//this part just shows how to use the results...
NSLog(@"route pointCount = %d", pointCount);
for (int c=0; c < pointCount; c++)
{
    NSLog(@"routeCoordinates[%d] = %f, %f", 
        c, routeCoordinates[c].latitude, routeCoordinates[c].longitude);
}

//free the memory used by the C array when done with it...
free(routeCoordinates);

Depending on the route, be prepared for hundreds or thousands of coordinates.

Best Answer

Related Solutions

Ios – How to draw a MKPolyline on a MapView

Ios – latitude and longitude points from MKPolyline

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