How to draw an arc on Google Maps in iOS?

Question

How to draw an arc between two coordinate points in Google Maps like in this image and same like facebook post in iOS ?

Answer 1

Objective-C version @Rouny answer

- (void)DrawCurvedPolylineOnMapFrom:(CLLocationCoordinate2D)startLocation To:(CLLocationCoordinate2D)endLocation
{
    GMSMutablePath * path = [[GMSMutablePath alloc]init];
    [path addCoordinate:startLocation];
    [path addCoordinate:endLocation];
    // Curve Line
    double k = 0.2; //try between 0.5 to 0.2 for better results that suits you
    CLLocationDistance d = GMSGeometryDistance(startLocation, endLocation);
    float h = GMSGeometryHeading(startLocation , endLocation);

    //Midpoint position
    CLLocationCoordinate2D p = GMSGeometryOffset(startLocation, d * 0.5, h);
    //Apply some mathematics to calculate position of the circle center
    float x = (1-k*k)*d*0.5/(2*k);
    float r = (1+k*k)*d*0.5/(2*k);
    CLLocationCoordinate2D c = GMSGeometryOffset(p, x, h + -90.0);

    //Polyline options
    //Calculate heading between circle center and two points
    float h1 =  GMSGeometryHeading(c, startLocation);
    float h2 = GMSGeometryHeading(c, endLocation);
    //Calculate positions of points on circle border and add them to polyline options
    float numpoints = 100;
    float step = ((h2 - h1) / numpoints);
    for (int i = 0; i < numpoints; i++) {
        CLLocationCoordinate2D pi = GMSGeometryOffset(c, r, h1 + i * step);
        [path addCoordinate:pi];
    }

    //Draw polyline
    GMSPolyline * polyline = [GMSPolyline polylineWithPath:path];
    polyline.map = mapView;
    polyline.strokeWidth = 3.0;
    NSArray *styles = @[[GMSStrokeStyle solidColor:kBaseColor],
                        [GMSStrokeStyle solidColor:[UIColor clearColor]]];

    NSArray *lengths = @[@5, @5];

    polyline.spans = GMSStyleSpans(polyline.path, styles, lengths, kGMSLengthRhumb);

    GMSCoordinateBounds * bounds = [[GMSCoordinateBounds alloc]initWithCoordinate:startLocation coordinate:endLocation];
    UIEdgeInsets insets = UIEdgeInsetsMake(20, 20, 20, 20);
    GMSCameraPosition * camera = [mapView cameraForBounds:bounds insets:insets ];
    [mapView animateToCameraPosition:camera];

}