YCCHMapClusterController solves the problem of displaying many annotations on an YMKMapView and is available under the MIT license.
Fork of [CCHMapClusterController] (https://github.com/choefele/CCHMapClusterController), see it for detailed info.
Changed to work with [Yandex Map Kit] (https://github.com/yandexmobile/yandexmapkit-ios)
Also see [this app] (https://itunes.apple.com/ru/app/moskovskie-skoly/id1140237737?mt=8) as example of usage.
todo: add example app with YMKMapView and clusters