Create custom shapes (Geofence) in MapKit, Swift 3

I need to create an application equal to this tutorial:

https://www.raywenderlich.com/136165/core-location-geofencing-tutorial

But I need that not draw circles as the area that active the notifications to the contrary I want that the user can draw a shapes custom and this is the area that active them notifications. It is an app type Snapchat Geofilters, here the reference:

https://www.snapchat.com/geofilters/submit.html

All this in the device (iPhone).

Create custom shapes (Geofence) in MapKit, Swift 3
 
 
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