Set up Google Apps on your iPhone
What do I need before getting started?
Before you can set up Google Apps on your iPhone to have instant access to your email, calendar and contacts, you need to have already obtained an Google Apps account. If you haven't got one yet, we can help you set up an account for you for free. What you will need is adminstrator access to your Google Apps account (you need to be able to log into your Google Apps account as an administrator.
Step 1: enable Sync to your Google Apps accounts from mobile devices
You can log into your Google Apps account at: apps.google.com/a/yourdomain. Once logged in, go to Service Settings from the top menu, and select Mobile. On the next screen, you need to enable Google Sync. You may have more options in terms of level of security if you are using the Premier edition.
Step 2: Set up Google Apps on your iPhone
First of all, go to settings on your iPhone, and tap on Mail, Contacts, Calendars as the image shows below.
On the next screen (the image above on the right), tap on "Add Account". On the next screen, tap on the first option from the top: Microsoft Exchange. Please note that you can only set up 1 Microsoft Exchange account on your iPhone.
You should then be taken to the next screen as shown below. You will need to choose which services that you would like to sync on your iPhone. Please note that you may modify this any time after the setup. Tap on Done when you finish.