Drawing a line between the coordinates in MKMapView - iphone

Question

I want to draw the lines between the coordinates in MKMapView..Here is the code
aRoute=[NSArray arrayWithObjects:[[CLLocation alloc] initWithLatitude:40.445418 longitude:-79.942714],[[CLLocation alloc] initWithLatitude:40.444469 longitude:-79.948628],[[CLLocation alloc] initWithLatitude:40.44569 longitude:-79.950388],[[CLLocation alloc] initWithLatitude:40.446967 longitude:-79.95053],[[CLLocation alloc] initWithLatitude:40.448874 longitude:-79.951715],[[CLLocation alloc] initWithLatitude:40.45134 longitude:-79.953175],[[CLLocation alloc] initWithLatitude:40.452213 longitude:-79.950895],[[CLLocation alloc] initWithLatitude:40.452564 longitude:-79.949838],[[CLLocation alloc] initWithLatitude:40.453528 longitude:-79.94641],[[CLLocation alloc] initWithLatitude:40.454109 longitude:-79.944487],[[CLLocation alloc] initWithLatitude:40.455858 longitude:-79.938618],[[CLLocation alloc] initWithLatitude:40.457224 longitude:-79.934069],[[CLLocation alloc] initWithLatitude:40.454777 longitude:-79.9932543],[[CLLocation alloc] initWithLatitude:40.453458 longitude:-79.931763],[[CLLocation alloc] initWithLatitude:40.452099 longitude:-79.931148],[[CLLocation alloc] initWithLatitude:40.451258 longitude:-79.930633],[[CLLocation alloc] initWithLatitude:40.449866 longitude:-79.929729],[[CLLocation alloc] initWithLatitude:40.448956 longitude:-79.932543],[[CLLocation alloc] initWithLatitude:40.44846 longitude:-79.934185],[[CLLocation alloc] initWithLatitude:40.447919 longitude:-79.937028], nil];
if (xapp.aRoute && xapp.aRoute .count > 0)
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor);
CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1.0);
CGContextSetAlpha(context, 0.5);
CGContextSetLineWidth(context, POLYLINE_WIDTH);
for (int i = 0; i < xapp.aRoute .count; i++) {
CLLocation* location =(CLLocation*) [xapp.aRoute objectAtIndex:i];
CLLocationCoordinate2D coordinate=CLLocationCoordinate2DMake(location.coordinate.latitude,location.coordinate.longitude);
NSLog(#"%f%f",coordinate.longitude,coordinate.latitude);
CGPoint point = [_mapView convertCoordinate:coordinate toPointToView:_mapView];
if (i == 0)
CGContextMoveToPoint(context, point.x, point.y);
else
CGContextAddLineToPoint(context, point.x, point.y);
NSLog(#"%f%f",point.x,point.y);
}
CGContextStrokePath(context);
}
Here the problem is convertCoordinate is not working for me.. I'm getting the CGPoints as {0,0} for all the coordinates

Answer 1

I write code from draw line on MapView are bellow...
-(void) updateRouteView
{
CGContextRef context = CGBitmapContextCreate(nil,
routeView.frame.size.width,
routeView.frame.size.height,
8,
4 * routeView.frame.size.width,
CGColorSpaceCreateDeviceRGB(),
kCGImageAlphaPremultipliedLast);
CGContextSetStrokeColorWithColor(context, lineColor.CGColor);
CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1.0);
CGContextSetLineWidth(context, 3.0);
for(int i = 0; i < routes.count; i++)
{
CLLocation* location1 = [routes objectAtIndex:i];
CGPoint point = [mapView convertCoordinate:location1.coordinate toPointToView:routeView];
if(i == 0)
{
CGContextMoveToPoint(context, point.x, routeView.frame.size.height - point.y);
}
else
{
CGContextAddLineToPoint(context, point.x, routeView.frame.size.height - point.y);
}
}
CGContextStrokePath(context);
CGImageRef image = CGBitmapContextCreateImage(context);
UIImage* img = [UIImage imageWithCGImage:image];
routeView.image = img;
CGContextRelease(context);
}
See this Demo Serendipitor
may you get some idea from this....