iphone - iOS/iPhone 上的正常运行时间卡住

Question

有人知道为什么我在使用以下方法时遇到奇怪的正常运行时间吗？

NSProcessInfo *processInfo = [NSProcessInfo processInfo];
NSTimeInterval systemUptime = [processInfo systemUptime];

最初几分钟，一切似乎都很好，但当我在数小时或数天后返回应用程序时，正常运行时间仍然相同:30 分钟，或 1 小时 34 分......它似乎在随机时刻卡住。主要在 iPhone 4 上(很少在模拟器或 iPad 上)

它可能与我展示它的方式有关:

+ (NSTimeInterval)uptime:(NSNumber **)days hours:(NSNumber **)hours mins:(NSNumber **)mins
{
    NSProcessInfo *processInfo = [NSProcessInfo processInfo];
        //START UPTIME///////
    NSTimeInterval systemUptime = [processInfo systemUptime];
        // Get the system calendar
    NSCalendar *sysCalendar = [NSCalendar currentCalendar];
        // Create the NSDates
    NSDate *date = [[NSDate alloc] initWithTimeIntervalSinceNow:(0-systemUptime)]; 
    unsigned int unitFlags = NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit;
    NSDateComponents *c = [sysCalendar components:unitFlags fromDate:date toDate:[NSDate date]  options:0]; 
        //NSString *uptimeString = [NSString stringWithFormat:@"%dd %dh %dmin", [c day],[c hour],[c minute]];
    *days = [NSNumber numberWithInt:[c day]];
    *hours = [NSNumber numberWithInt:[c hour]];
    *mins = [NSNumber numberWithInt:[c minute]];
    [date release];
        //END UPTIME////////

    return systemUptime;
}

在后面的代码中:

NSNumber *uptimeDays, *uptimeHours, *uptimeMins;
[CJGDevice uptime:&uptimeDays hours:&uptimeHours mins:&uptimeMins];
NSString *uptimeString = [NSString stringWithFormat:@"%@d %@h %@min",
                          [uptimeDays stringValue],
                          [uptimeHours stringValue],
                          [uptimeMins stringValue]];

编辑:在 iPad 和 iPhone 上记录了 3 天的结果后，我可以看到这个正常运行时间是错误的，时间运行得太慢，我们等待的时间越长就越明显

Answer 1

这个方法可以解决问题:

- (time_t)uptime
{
    struct timeval boottime;
    int mib[2] = {CTL_KERN, KERN_BOOTTIME};
    size_t size = sizeof(boottime);
    time_t now;
    time_t uptime = -1;

    (void)time(&now);    

    if (sysctl(mib, 2, &boottime, &size, NULL, 0) != -1 && boottime.tv_sec != 0) 
    {
        uptime = now - boottime.tv_sec;
    }
    return uptime;
}

感谢 Alastair Stuart 的 link .