Get the boot time in objective c - objective-c

Question

how can i get the boot time of ios in objective c ?
Is there a way to get it?

Answer 1

Don't know if this will work in iOS, but in OS X (which is essentially the same OS) you would use sysctl(). This is how the OS X Unix utility uptime does it. Source code is available - search for "boottime".
#include <sys/types.h>
#include <sys/sysctl.h>
// ....
#define MIB_SIZE 2
int mib[MIB_SIZE];
size_t size;
struct timeval boottime;
mib[0] = CTL_KERN;
mib[1] = KERN_BOOTTIME;
size = sizeof(boottime);
if (sysctl(mib, MIB_SIZE, &boottime, &size, NULL, 0) != -1)
{
// successful call
NSDate* bootDate = [NSDate dateWithTimeIntervalSince1970:boottime.tv_sec];
}
The restricted nature of programming in the iOS sandboxed environment might make it not work, I don't know, I haven't tried it.

Answer 2

I took JeremyP's answer, gave the result the full microsecond precision, clarified the names of local variables, improved the order, and put it into a method:
#include <sys/types.h>
#include <sys/sysctl.h>
// ....
+ (nullable NSDate *)bootDate
{
// nameIntArray and nameIntArrayLen
int nameIntArrayLen = 2;
int nameIntArray[nameIntArrayLen];
nameIntArray[0] = CTL_KERN;
nameIntArray[1] = KERN_BOOTTIME;
// boot_timeval
struct timeval boot_timeval;
size_t boot_timeval_size = sizeof(boot_timeval);
if (sysctl(nameIntArray, nameIntArrayLen, &boot_timeval, &boot_timeval_size, NULL, 0) == -1)
{
return nil;
}
// bootSince1970TimeInterval
NSTimeInterval bootSince1970TimeInterval = (NSTimeInterval)boot_timeval.tv_sec + ((NSTimeInterval)boot_timeval.tv_usec / 1000000);
// return
return [NSDate dateWithTimeIntervalSince1970:bootSince1970TimeInterval];
}