Set up Google Apps on your iPhone with your native iphone apps including (mail, calendar and contacts).
1. Find settings on your iphone, select mail, contacts, calendars.
2. Select Add Account
3. Select Google
4. Enter account information
6. Click next and select features you want to sync. To be able to accept invite, create new events you must sync calendars. When syncing google contacts you have the option to sync with your Google contacts, while keeping or deleting contacts on your