Apple iPhone’s iOS doesn’t allow users to select a default map/navigation app.
Here is how to use another map/navigation app on an iPhone.
- Click the NAVIGATION button in the Route 66 Ultimate Guide app. This will open with Apple Maps by default.
- In the Apple Maps app, tap the “CAR” button.
- Tap the “SHARE” button.
- Tap “Transport apps”.
- Select the map/navigation app you want to use.
NOTE: This process is not actually changing your default map/navigation app. Unfortunately, this is the only option available, until Apple allows users to set their preferred (default) apps within the iPhone’s iOS.