You can sync Google Calendar with the Calendar app that comes on your iPhone or iPad.
- Open the Settings app on your iPhone or iPad .
- Touch Mail, Contacts, Calendars > Add account > Google.
- Enter your email address > Next.
- Enter your password. If you have iOS 7 or below and you use 2-Step Verification, enter an app password instead of your regular password.
- Touch Next.
- Emails, contacts, and calendar events will now sync directly with your Google Account. To sync only your calendar, turn off the other services.
- Open the Calendar app on your iPhone to see your Google Calendar events.