how to get data usage(cellular or wifi)breakdown of other applications used, from my application

Question

我想从将在后台运行的应用程序中确切了解本机电子邮件应用程序的数据使用情况。我能够获得iPhone的全部数据使用情况，但无法获取细分使用情况...

Answer 1

There is no public API available for this information. Apple do not provide application's access to it. As of iOS 7, you can see a breakdown of cellular data consumed on a per app basis in the System app.

Apps that claim to provide data usage statistics do it in one of two ways. They have the user run everything through a proxy server (bad), or they use a unix utility that's rather inaccurate because it resets on system reboot (I'm simplifying quite a bit here).

Basically, there's no supported method to do this. Any app that does claim to do it is using a half-arsed implementation that isn't particularly accurate, or has substantial privacy concerns. If you just need to know cellular data consumption for your own reference you can use the System app on iOS 7.