Hacker News Reader

Between the iOS 6 launch in fall 2012 and December 2012 Google Maps was unavailable on iOS.

"In June 2012, Apple announced that they would replace Google Maps with their own maps service from iOS 6. However, on December 13, 2012, Google announced the availability of Google Maps in the Apple App Store, starting with the iPhone version. Just hours after the Google Maps iOS app was released, it became the top free app in the App Store."

https://en.wikipedia.org/wiki/Google_Maps

When Apple replaced the first-party Google Maps app with its own Apple Maps, and then Google had to release a new third-party Maps app for iOS quickly.

IIRC there was a migration period when apple and google "divorced" on iOS, and the standalone google apps were in the making. Cannot pinpoint the year by memory.