Question

I’m trying to convert timestamp (NSTimeInterval) to date format. I’m getting the correct current date (day-month-year) but the time is not right. Here is my code. How do I fix it to get the current time correctly? Thanks in advance.

- (NSString*)formatTimestamp:(NSTimeInterval)timeStamp
{
    NSDate *date = [NSDate dateWithTimeIntervalSinceNow:timeStamp];
    NSDateFormatter *formatter=[[NSDateFormatter alloc]init];
    [formatter setDateFormat:@"dd-MM-yyyy HH:mm:ss:SSS zzz"];
    NSString *dateString=[formatter stringFromDate:date];
    [formatter release];
    return dateString;
}

Answer 1

Maybe I misunderstood something but I think your comparison is not right…

NSLog‘s time is current time and UIEvent‘s timestamp is the number of seconds since system startup (and you add it to current time with [NSDate dateWithTimeIntervalSinceNow:])…

If you want absolute datetime of an UIEvent you need to get system startup date first, which is not so easy… and then add UIEvent‘s timestamp.

You can use

lastRebootTime = [[NSDate date] addTimeInterval:-[self secondsSinceLastReboot]];

with

- (NSTimeInterval)secondsSinceLastReboot
{
    // get the timebase info -- different on phone and OSX
    mach_timebase_info_data_t info;
    mach_timebase_info(&info);

    // get the time
    uint64_t absTime = mach_absolute_time();

    // apply the timebase info
    absTime *= info.numer;
    absTime /= info.denom;

    // convert nanoseconds into seconds
    return (NSTimeInterval) ((double)absTime / 1000000000.0);
}

Cf. Generating iPhone UIEvent Timestamps