System Uptime

Programming Languages Swift
Bjvb09 OP
Created May ’18
Replies 7
Boosts 0
Views 8.9k
Participants 5

Hello! I have a question. Is there a way to get the last time that the phone was booted? I found this:


ProcessInfo.processInfo.systemUptime


But it give me the time since the last time the phone was turned off, and I need to know the time since the last time the phone was switched on. I don't know if this is possible.

Answered by DTS Engineer in 309633022 
systemUptime
is not the droid you’re looking for. However, the problem is not what you think it is. You wrote:

But it give me the time since the last time the phone was turned off …

which is incorrect. Rather, the problem is sleep. 

systemUptime
only counts time while the system has been awake, and our devices sleep a lot.

You can get the boot time (that is, the clock time when the system booted) using the 

kern.boottime
sysctl. Here’s a snippet: 
func bootTime() -> Date? {
    var tv = timeval()
    var tvSize = MemoryLayout<timeval>.size
    let err = sysctlbyname("kern.boottime", &tv, &tvSize, nil, 0);
    guard err == 0, tvSize == MemoryLayout<timeval>.size else {
        return nil
    }
    return Date(timeIntervalSince1970: Double(tv.tv_sec) + Double(tv.tv_usec) / 1_000_000.0)
}

Be aware that this time will change if the system clock changes, that is, the value is the boot time relative to the current system clock.

Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware 

let myEmail = "eskimo" + "1" + "@apple.com"
Replies  7
Boosts  0
Views  8.9k
Participants  5
Claude31 OP
May ’18

That's a bit surprising, as doc states :


var systemUptime: TimeInterval

The amount of time the system has been awake since the last time it was restarted.

0
Bjvb09 OP
May ’18

Yes, I read that, but I think is a little bit ambiguous. So I already tried and the behaviour that I described above is what I got. So I'm looking for other options.


Thank you for reading.

0
Claude31 OP
May ’18

If systemUptime does not show the amount of time the system has been awake since the last time it was restarted,

you should file a bug report.

0
DTS Engineer OP
Apple
May ’18
Accepted Answer 
systemUptime
is not the droid you’re looking for. However, the problem is not what you think it is. You wrote:

But it give me the time since the last time the phone was turned off …

which is incorrect. Rather, the problem is sleep. 

systemUptime
only counts time while the system has been awake, and our devices sleep a lot.

You can get the boot time (that is, the clock time when the system booted) using the 

kern.boottime
sysctl. Here’s a snippet: 
func bootTime() -> Date? {
    var tv = timeval()
    var tvSize = MemoryLayout<timeval>.size
    let err = sysctlbyname("kern.boottime", &tv, &tvSize, nil, 0);
    guard err == 0, tvSize == MemoryLayout<timeval>.size else {
        return nil
    }
    return Date(timeIntervalSince1970: Double(tv.tv_sec) + Double(tv.tv_usec) / 1_000_000.0)
}

Be aware that this time will change if the system clock changes, that is, the value is the boot time relative to the current system clock.

Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware 

let myEmail = "eskimo" + "1" + "@apple.com"
2
Bjvb09 OP
May ’18

Eskimo! Thank you very much! This is the third time you save me.

0
manpunia OP
Jan ’21
@eskimo, we are using this logic to identify device reboot, But without even device restart getting different value for tv. Getting difference up to 30 seconds. What may be possible root cause of this issue? any pointers.
0
DTS Engineer OP
Apple
Sep ’24

I most commonly see folks ask about this because they’re trying to get a secure timestamp. If you come here for that reason, you can find my latest through in this post.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

0
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