How to get the CPU usage of iPhone/iPad?

I saw in A+ monitor, it can show CPU Idle, CPU usage, CPU System. Which API should be used to get the these information? I have searched and I use the getloadavg function, but it can only return the CPU usage. Also it is not co开发者_开发技巧rrectly for it will always be more than 90%.

Thanks!

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Most of these can be retrieved using the appropriate sysctl() selectors.