iOS System Uptime

systemUptime.swift

    static func systemUptime() -> TimeInterval {
        var currentTime = time_t()
        var bootTime    = timeval()
        var mib         = [CTL_KERN, KERN_BOOTTIME]
        // NOTE: Use strideof(), NOT sizeof() to account for data structure
        // alignment (padding)
        // http://stackoverflow.com/a/27640066
        // https://devforums.apple.com/message/1086617#1086617
        var size = MemoryLayout<timeval>.stride
        let result = sysctl(&mib, u_int(mib.count), &bootTime, &size, nil, 0)
        if result != 0 {
            #if DEBUG
            print("ERROR - \(#file):\(#function) - errno = "
                + "\(result)")
            #endif
            return 0
        }
        // Since we don't need anything more than second level accuracy, we use
        // time() rather than say gettimeofday(), or something else. uptime
        // command does the same
        time(&currentTime)
        let uptime = currentTime - bootTime.tv_sec
        
        return TimeInterval(uptime)
    }