快速检测一段iOS代码执行的效率函数

uint64_t begin = mach_absolute_time();

uint64_t end = mach_absolute_time();
NSLog(@"本次用时-------------%g s",MachTimeToSecs(end - begin));

// 用于统计时间
double MachTimeToSecs(uint64_t time)
{
    mach_timebase_info_data_t timebase;
    mach_timebase_info(&timebase);
    return (double)time * (double)timebase.numer / (double)timebase.denom / 1e9;
}