X code 4.5 中Required background modes
1.App plays audio
2.App registers for location updates
3.App provides Voice over IP services
4.App processes Newsstand Kit downloads
5.App communicates with an accessory
6.App communicates using CoreBluetooth
7.App shares data using CoreBluetooth
－－－－－－－－－－
Xcode 4.3.2中
1.App plays audio
2.App registers for location updates
3.App provides Voice over IP services
－－－－
Xcode 4.5以前SDK版本最新是5.1,Xcode 4.5.2 的SDk最新版本是6.0 ，这说明IOS 6中增加了4种后台运行模式即4,5,6,7
优酷客户端后台下载怎么做到的呢？
http://dev.ppios.com/2012/12/ios-background-running-methods/
http://www.cocoachina.com/bbs/simple/?t89479.html