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2014/10/15 ¤U¤È 10:11:57

iphone Programming Glossary: nanoseconds

What is mach_absolute_time based on on iPhone

http://stackoverflow.com/questions/1450737/what-is-mach-absolute-time-based-on-on-iphone

form you have to modify it by the result from mach_timebase_info a ratio which will return billionth of seconds or nanoseconds . To make this more usable I use a function like the one below #include mach mach_time.h int getUptimeInMilliseconds const..

What are the tradeoffs between performSelector:withObject:afterDelay: and dispatch_after

http://stackoverflow.com/questions/6205998/what-are-the-tradeoffs-between-performselectorwithobjectafterdelay-and-dispat

minimum amount of time. On the other hand dispatch_after gives you a control which seems in principle at the level of nanoseconds this is what I get from Apple docs but I have never used it and I don't think that on an iPhone you would get that possibly..

How do I accurately time how long it takes to call a function on the iPhone?

http://stackoverflow.com/questions/646815/how-do-i-accurately-time-how-long-it-takes-to-call-a-function-on-the-iphone

How do I do this iphone benchmarking share improve this question You can use mach_absolute_time to measure in nanoseconds. #import mach mach_time.h uint64_t startTime 0 uint64_t endTime 0 uint64_t elapsedTime 0 uint64_t elapsedTimeNano 0 mach_timebase_info_data_t..

CoreAudio AudioTimeStamp.mHostTime clock frequency?

http://stackoverflow.com/questions/675626/coreaudio-audiotimestamp-mhosttime-clock-frequency

on the iPhone. When I'm running my application in the simulator the AudioTimeStamp.mHostTime appears to be in nanoseconds 1 000 000 000th of a second whereas when running on my device iPod Touch 2G the frequency appears to be about 6 000 000th.. on OS X there is a function AudioConvertHostTimeToNanos in CoreAudio CoreAudioTypes.h to convert HostTime to and from nanoseconds but this function is not in the iPhone headers. Is there any way to find out the rate of mHostTime at runtime or to convert.. is not in the iPhone headers. Is there any way to find out the rate of mHostTime at runtime or to convert to seconds nanoseconds or any other unit Will this value change between software or hardware versions like it has between the simulator and my..