If you have more than one Google calendar, here is how to sync multiple Google calendar to your iPhone/iPad.
- Read the Setup instructions to sync your Google account with your iPhone/iPad.
- Browse with iPhone/iPad Safari to http://m.google.com/sync.
- Change the language to English (US).
- On http://m.google.com/ click on Sync or browse to http://m.google.com/sync. And maybe you must login with your Google account.
- Select the device and configure the calendars.
- In the iPhone/iPad Calendar app you must refresh to sync the calendars.