iOS NSDateFormatter and Compare Two Date

NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setLocale:[NSLocale currentLocale]];
[dateFormat setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];

[dateFormat setDateFormat:@"yyyy/MM/dd"];
NSDate *date = [dateFormat dateFromString:@"2013/5/23"];

NSString *selectionString = [dateFormat stringFromDate:date];

SO Link(http://stackoverflow.com/questions/12721553/get-time-from-nsdate-returns-nil/12721934#12721934)

Imp Link (http://ios.eezytutorials.com/)

The most commonly used date format specifiers are (keep in mind that they are case sensitive):

• y = year
• Q = quarter
• M = month
• w = week of year
• W = week of month
• d = day of the month
• D = day of year
• E = day of week
• a = period (AM or PM)
• h = hour (1-12)
• H = hour (0-23)
• m = minute
• s = second

In general, the number of characters in a specifier determine the size of date field. Let’s use an example to illustrate date formatting.

eg. Input date = 2011-05-01 Sunday

1-character = 1-digit/character number or word (if number/word can’t be 1 character long then abbreviation or fullname is displayed).

[dateFormatter setDateFormat:@"E, d M y"];  // Output: Sun, 1 5 2011

2-character = 2-digit/character number or word (if number/word can’t be 2 character long then abbreviation is displayed).

[dateFormatter setDateFormat:@"EE, dd MM yy"];  // Output: Sun, 01 05 11

3-character = 3-digit/character number or word, or abbreviation (generally).

[dateFormatter setDateFormat:@"EEE, ddd MMM yyy"];  // Output: Sun, 001 May 2011

4-character = full name (generally).

[dateFormatter setDateFormat:@"EEEE, dddd MMMM yyyy"];  // Output: Sunday, 0001 May 2011

Here’s the weird part though, if you specify 5 E’s, you get an rather unexpected output. You would think that the output date field would be longer than 1 character:

[dateFormatter setDateFormat:@"EEEEE, ddddd MMMMM yyyyy"];  // Output: S, 00001 M 2011

Compare Two Date

NSDateFormatter *formatter = [[[NSDateFormatter alloc] init] autorelease];
    NSDate *serDate;

    NSDate *endDate;

    [formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];

    serDate = [formatter dateFromString:@"2012-12-07 7:17:58"];

    endDate = [formatter dateFromString:@"2012-12-07 08:43:30"];
    NSTimeInterval timeDifference = [endDate timeIntervalSinceDate:serDate];

    double minutes = timeDifference / 60;

    double hours = minutes / 60;

    double seconds = timeDifference;

    double days = minutes / 1440;
    NSLog(@" days = %.0f,hours = %.2f, minutes = %.0f,seconds = %.0f", days, hours, minutes, seconds);


    if (hours > 1.30)
        return 1;
    else
        return 0;