DateFormats a: AM/PM A:0~86399999(Millisecond of Day) c/cc:1~7(Day of Week) ccc:Sun/Mon/Tue/Wed/Thu/Fri/Sat cccc:Sunday/Monday/Tuesday/Wednesday/Thursday/Friday/Saturday d:1~31(0 padded Day of Month) D:1~366(0 padded Day of Year) e:1~7(0 padded Day of Week) E~EEE:Sun/Mon/Tue/Wed/Thu/Fri/Sat EEEE:Sunday/Monday/Tuesday/Wednesday/Thursday/Friday/Saturday F:1~5(0 padded Week of Month, first day of week =Monday) g:JulianDayNumber(number of days since 4713 BC January1) G~GGG: BC/AD (EraDesignatorAbbreviated) GGGG:BeforeChrist/AnnoDomini h:1~12(0 padded Hour(12hr)) H:0~23(0 padded Hour(24hr)) k:1~24(0 padded Hour(24hr) K:0~11(0 padded Hour(12hr)) L/LL:1~12(0 padded Month) LLL:Jan/Feb/Mar/Apr/May/Jun/Jul/Aug/Sep/Oct/Nov/Dec LLLL:January/February/March/April/May/June/July/August/September/October/November/December m:0~59(0 padded Minute) M/MM:1~12(0 padded Month) MMM:Jan/Feb/Mar/Apr/May/Jun/Jul/Aug/Sep/Oct/Nov/Dec MMMM:January/February/March/April/May/June/July/August/September/October/November/December q/qq:1~4(0 padded Quarter) qqq: Q1/Q2/Q3/Q4 qqqq:1st quarter/2nd quarter/3rd quarter/4th quarter Q/QQ:1~4(0 padded Quarter) QQQ: Q1/Q2/Q3/Q4 QQQQ:1st quarter/2nd quarter/3rd quarter/4th quarter s:0~59(0 padded Second) S:(rounded Sub-Second) u:(0 padded Year) v~vvv:(General GMT TimezoneAbbreviation) vvvv:(General GMT TimezoneName) w:1~53(0 padded Week of Year,1st day of week =Sunday, NB:1st week of year starts from the last Sunday of last year) W:1~5(0 padded Week of Month,1st day of week =Sunday) y/yyyy:(FullYear) yy/yyy:(2DigitsYear) Y/YYYY:(FullYear, starting from the Sunday of the 1st week of year) YY/YYY:(2DigitsYear, starting from the Sunday of the 1st week of year) z~zzz:(Specific GMT TimezoneAbbreviation) zzzz:(Specific GMT TimezoneName) Z:+0000(RFC 822Timezone)How to Use:NSDateFormatter*dateFormatter =[[NSDateFormatter alloc] init];[dateFormatter setDateFormat:@"dd/MM/yyyy hh:mm:ss a"];NSLog(@"%@",[dateFormatter dateFromString:@"12/12/2012 12:12:12 AM"]);
更完整的需要参考
http://unicode.org/reports/tr35/tr35-10.html#Date_Format_Patterns