Question

In Xcode 4, there is a Myproject.entitlements file.

What’s it for?

In general, what are the “entitlements”? What are they for?

Answer 1

It’s related to iCloud and push notifications (on iOS and Mac OS X) and the App Sandbox feature (in OS X only).

There is more information in Entitlement Key Reference. App Sandbox is documented in App Sandbox Design Guide:

An app that is not sandboxed has access to all user-accessible system
resources—including the built-in camera and microphone, network
sockets, printing, and most of the file system. If successfully
attacked by malicious code, such an app becomes a hostile agent with
wide-ranging potential to inflict harm.

When you enable App Sandbox for your app, you remove all but a minimal
set of privileges and then deliberately restore them, one-by-one,
using entitlements. An entitlement is a key-value pair that identifies
a specific capability, such as the capability to open an outbound
network socket.