Access Information from Apple’s Apps
Your iOS app can access the user’s information in the Contacts app and display that information in a different way or use it as information in your application. For example, a user could enter the name and address of a hotel, and the application would file it in the user’s Contacts database.
Then, when the user arrives in New York City, for example, the application can retrieve the address from the Contacts app and display directions. What’s more, your app can also present standard interfaces for picking and creating contacts.
What you can do with Contacts, you can do in a similar fashion with the Calendar app. Your app can remind a user when to leave for the airport or create calendar events based on what’s happening this week in New York. These events show up in the Calendar app and in other apps that support that framework.
Your app can also access the Photo library in the Photos app, not only to display photos but also to use or even modify them. For example, Apple’s Photos app lets you add a photo to a contact, and many applications enable you to edit your photos on the device itself. You can develop your own photo-editing app for the iPhone or iPad using, for example, Apple’s Core Image framework.
iOS (the iPad and iPhone operating system) provides support for Copy, Cut, and Paste operations within and between applications. It also provides a context-sensitive Edit menu that can display the Copy, Cut, Paste, Select, Select All, and Delete system commands. That means that while each iOS application is generally expected to play only in its own sandbox, you actually do have ways to send small amounts of data between applications.