ios7新特性nsurlsession初探

ios7引入了nsurlsession，通過它可以支援後臺相關的網路操作的新特性。讓我們看看它有哪些好處：

Why Use NSURLSession?

Why should you use NSURLSession? Well, it brings you a number of new advantages and benefits:

• Background uploads and downloads: With just a configuration option when the NSURLSession is created, you get all the benefits of background networking. This helps with battery life, supports UIKit multitasking and uses the same delegate model as in-process transfers.
• Ability to pause and resume networking operations: As you will see later, with the NSURLSession API any networking task can be paused, stopped, and restarted. No NSOperation sub-classing necessary.
• Configurable container: Each NSURLSession is the configurable container for putting requests into. For example, if you need to set an HTTP header option you will only need to do this once and each request in the session will have the same configuration.
• Subclassable and private storage: NSURLSession is subclassable and you can configure a session to use private storage on a per session basis. This allows you to have private storage objects outside of the global state.

• Improved authentication handling: Authentication is done on a specific connection basis. When using NSURLConnection if an authentication challenge was issued, the challenge would come back for an arbitrary request, you wouldn’t know exactly what request was getting the challenge. WithNSURLSession, the delegate handles authentication.