To sync with Google Calendar via GMail(CalDAV), follow these steps:
1. Open the Settings application on your device’s home screen.
2. Open Mail, Contacts, Calendars.
3. Select Add Account…
4. Select GMail. (If you already have gmail setting, jump to 6. )
5. Enter your account information:
- In the Name field, enter your name.
- In the Address field, enter your full Google Account or Google Apps email address.
- In the Password field, enter your Google Account or Google Apps password.
- In the Description field, enter the name you’d like to appearon the account.
- Select Next at the top of your screen.
6. Calendar switch ON, then save.
After you’ve completed setup, open the Calendar app on your device and syncing will automatically begin. By default only your primary calendar will be synced to your device.
If you want to use additional calendars (Multiple calendars on Google Calendar), you need additional configulation.(please refer here.)