MKUserlocation annotation

I need to put tens of circles to my mapkit app, and I'm hesitant to choose between MKCircle and MKAnnotation because I want:

1. Animation on the circle. Doable in annotations

2. Fixed meter size of the circle. Doable in MKCircles


However, I found that MKUserlocationView for user location pin is an annotation but also has fixed size of the "pulsing circle" based on the zoom level(stays constant with the meter size). How can I achieve that in custom annotation?


I thought about changing the size in a separate function but it would be too bulky and lagyy, and I figure that there must be some other way to achieve constant size in annotations.


Is there a way to mimic that behavior of fixed meter size and animate the view?