Most people can probably work out for themselves how to set up their Gmail account on their iPhone, iPad or iTouch. It's fairly straight-forward and to be honest the iOS does most of the work for you. Going about it the easy way will allow you to sync you Mail, Calendars and Notes. That's great!
However, something is missing from this picture. Did you notice that you don't have any option here to sync your Gmail contacts? So what do you do? The answer is, you go about it a different way.
When you go to Settings and choose Mail, Contacts & Calendars, you get an option to add a new account. Immediately you are presented with a list of possible options, one of which is Gmail. It would seem logical to select Gmail, as you are trying to add a Gmail account. And yes, that would be the normal procedure. However, Gmail can also be added an a Microsoft Exchange account - and that's where you get the extra features.
So, by selecting Microsoft Exchange as shown in this image, you can add your Gmail account as an Exchange account and get access to contact syncing. The thing is, you need to know a couple of extra settings to do that and that's a bit tricky if you don't know where to look. So here they are:
Email: put in your gmail address
Domain: you can leave this blank
Username: put in your email address again
Password: enter your gmail password
Description: enter something like "Gmail"
Now here's the trick. When you press the Next button, a new field will appear called Server. In this field, you need to enter "m.google.com" (without the quotation marks). Then press the Next button.
Voila! You can now enable contact syncing on the as well as Mail and Calendars. If you now go to your Contacts app you will see your contacts starting to appear. They will continuing appearing until the sync is complete and you have all your contacts!