If you are a bit of a command-line junkie and ever wanted to use APIs but wished you could get that data straight from your favorite shell, GoogleCL is for you. GoogleCL is a new open source project that allows you to utilize major Google APIs without writing code. It defines a set of commands that you can use as command-line utilities and access a number of Google services. For example, you can upload pictures to Google Picasa Web, create a new event in your Google Calendar, upload a blog post to Google Blogger, export your contacts to a file and much more.
Use this quickstart tutorial from Google Developers to build a simple iOS application that makes requests to Gmail’s API, which provides fine-grained access to Gmail features.