creating formatted NSDate using NSDateFormatter or mktime

Question

I'm just trying to create a NSDate object with string as:2011-02-10 4:30:45

Take a look at the code:

Approach OBJC:

-(NSDate *)get_date_df:(NSString *)dstr
{
    NSLog(@"1> %@",dstr);

    NSDateFormatter *df_in = [[[NSDateFormatter alloc] init]autorelease];
    [df_in setDateFormat:@"yyyy-MM-dd HH:mm:ss"];   
    NSDate *d = [df_in dateFromString:dstr];

    NSLog(@"2> %@",d);

    NSLog(@"3> %@",[df_in stringFromDate:d]);

    return d;
}

And here's the output:

1> 2011-02-10 4:30:45
2> 2011-02-09 23:00:45 +0000
3> 2011-02-10 04:30:45

So why is 2> getting printed wrong?
Suppose at 2011-02-10 4:20:45, I try setting up a LocalNotification with that date, it fires instantly because the processor assumes the time is already expired!

UILocalNotification *lnf = [[UILocalNotification alloc] init];
[lnf setFireDate:[self get_date_df:@"2011-02-10 4:30:45"]];
[lnf setAlertBody:@"WTF"];
[[UIApplication sharedApplication]scheduleLocalNotification:lnf];
[lnf release];

And, I've already tried setting up various TimeZones and NSLocale for en_US, en_FR. No help.

Approach C:

And FYI now I'm switching to C, trying something with:

-(NSDate *)get_date_c:(const char *)date_str
{
    char date[10][6] = {0};
    sscanf(date_str,"%[0-9] - %[0-9] - %[0-9] %[0-9] : %[0-9] : %[0-9]",date[0],date[1],date[2],date[3],date[4],date[5]);   

    struct tm *t_info = (struct tm *)malloc(sizeof(struct tm));
    t_info->tm_sec = atoi(date[5]);
    t_info->tm_min = atoi(date[4]);
    t_info->tm_hour = atoi(date[3]);
    t_info->tm_mday = atoi(date[2]);
    t_info->tm_mon = atoi(date[1]);
    t_info->tm_year = atoi(date[0]);
    NSLog(@"ans: %f",(double)mktime(t_info));
    NSDate *d = [NSDate dateWithTimeIntervalSince1970:mktime(t_info)];
    free(t_info);
    return d;
}

Output: ans: -1.000000
There again I'm stuck with converting time_t to NSTimeInterval.
So, thanks in advance if you could help me out with any approach :(

Answer 1

In your input string and format yyyy-MM-dd HH:mm:ss you didn't specify the timezone. So it defaults to UTC.