Change the image's origin of map annotation view?

Question

The regular annotation pin's origin is in the middle of the bottom so, the pin always point to the same place.

But when I add my custom image, its origin is the center of the image, so every zoom in or out, the bottom of my image point to a different place.

Here my pin is supposed to point to the center of paris BUT

but when I zoom in, the bottom of my pin isn't pointing to the center of Paris.

I'm trying with the CGRect.origin but didn't get anything useful.

Here is my code:

- (MKAnnotationView *)mapView:(MKMapView *)theMapView viewForAnnotation:(id <MKAnnotation>)annotation
{
    MKAnnotationView * customPinView = [[MKAnnotationView alloc] init];
    UIImage * img = [UIImage imageNamed:@"waterPin.png"] ;
    CGRect resizeRect;
    resizeRect.size.height = 40;
    resizeRect.size.width = 40;
    resizeRect.origin = (CGPoint){0.0f, 0.0f};
    UIGraphicsBeginImageContext(resizeRect.size);
    [img drawInRect:resizeRect];
    UIImage *resizedImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    customPinView.image = resizedImage;
    return customPinView;
}

Answer 1

MKAnnotationView has a centerOffset property which you can try setting to adjust the image offset:

customPinView.centerOffset = CGPointMake(xOffset,yOffset);

Unrelated, but you should use initWithAnnotation instead of just init for creating an MKAnnotationView.
It also wouldn't hurt to use dequeueReusableAnnotationViewWithIdentifier and implement annotation view re-use to improve performance.

I would also suggest not programmatically resizing the image in the delegate method and instead using an already-resized image to begin with. Then you can just do customPinView.image = [UIImage imageNamed:@"resizedWaterPin.png"]; without spending run-time resizing the annotation images every time.