The Apple closed garden is a pretty one but it's closed nonetheless.
As such, it can be tricy to get your data back from your iPhone. Here are some tips of how to export your data so that you can use it standard formats.
The standard format for contacts is
Once you have contacts in this format they can be imported to your Nest account and synced with any other service via
To get your contacts exported in this format, the simplest way is to install an export application on your iPhone.
We've had good success with the app called Contacts Backup & Transfer.
It's free and works on older versions of iOS too.
To export, just install the app, hit the backup button and then email the .vcf file to yourself.
You can read the exported files using any application that reads SQLite files, for instance DBBrowser.