I have decided to use Google Maps SDK for iOS. There's an instruction for obtaining the API key through Google APIs Console:
- Create an API project in the Google APIs Console.
- Select the Services pane in your API project, and enable the Google Maps SDK for iOS. This displays the Google Maps Terms of Service.
- Select the API Access pane in the console, and click Create new iOS key.
- Enter one or more bundle identifiers as listed in your application's .plist file, such as com.example.myapp.
- Click Create.
- In the API Access page, locate the section Key for iOS apps (with bundle identifiers) and note or copy the 40-character API key.
But I have no such thing as Google Maps SDK for iOS in Services. Does Google no longer support iOS API keys?