返回值均为毫秒
ios
#include <mach/mach_time.h>
uint64_t time = mach_absolute_time();
mach_timebase_info_data_t timebase;
mach_timebase_info(&timebase);
return (double)time * (double)timebase.numer /
(double)timebase.denom / 1e6;
mac
#include <CoreServices/CoreServices.h>
#include <mach/mach_time.h>
Nanoseconds timeNano;
uint64_t time = mach_absolute_time();
timeNano = AbsoluteToNanoseconds( *(AbsoluteTime *) &time);
return (* (uint64_t *)&timeNano) / 1000000 ;