Apple Maps developer: pricing?

I couldn't find anything official, but I hope this helps:

Apple has no limits on access to their location search API

Source

According to Apple developer site it's no limits, as long as the app is well-written.

There are no request limits per app or developer ID, so well-written apps that operate correctly should experience no problems. However, throttling may occur in a poorly written app that creates an extremely large number of requests.

I was looking for that information once and what I found out that there are no limit for geocoding, however it is reasonable to rethink the way you send requests to make them as few as possible.

Apple says:

Send at most one geocoding request for any one user action.

When you want to update the user’s current location automatically (such as when the user is moving), issue new geocoding requests only when the user has moved a significant distance and after a reasonable amount of time has passed. For example, in a typical situation, you should not send more than one geocoding request per minute.