iOS开发--获取时间

取得当前的年月日，当前的时分秒获得，周几和星期几获得

NSDate*date = [NSDate date];

NSCalendar*calendar = [NSCalendar currentCalendar];

NSDateComponents*comps;

// 年月日获得

comps =[calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit |NSDayCalendarUnit)

                                      fromDate:date];

NSIntegeryear = [comps year];

NSIntegermonth = [comps month];

NSIntegerday = [comps day];

NSLog(@"year:%d month: %d, day: %d", year, month, day);

//当前的时分秒获得

comps =[calendar components:(NSHourCalendarUnit | NSMinuteCalendarUnit |NSSecondCalendarUnit)

                                      fromDate:date];

NSIntegerhour = [comps hour];

NSIntegerminute = [comps minute];

NSIntegersecond = [comps second];

NSLog(@"hour:%d minute: %d second: %d", hour, minute, second);

// 周几和星期几获得

comps =[calendar components:(NSWeekCalendarUnit | NSWeekdayCalendarUnit |NSWeekdayOrdinalCalendarUnit)

                                      fromDate:date];

NSInteger week = [comps week]; // 今年的第几周

NSIntegerweekday = [comps weekday]; // 星期几（注意，周日是“1”，周一是“2”。。。。）

NSIntegerweekdayOrdinal = [comps weekdayOrdinal]; // 这个月的第几周

NSLog(@"week:%d weekday: %d weekday ordinal: %d", week, weekday, weekdayOrdinal);

NSDateFormatter*dateFormatter = [[NSDateFormatter alloc]init];

       if(dateSwitch.on)

       [dateFormattersetDateFormat:@"dd-MMM-yyy,hh:mm:ss"];

       else

       [dateFormatter setDateFormat:@"hh:mm:ss"];

       labelTime.text = [dateFormatter stringFromDate:[NSDatedate]];

       labelTime.font = [UIFontsystemFontOfSize:fontSlider.value];

       [dateFormatter release];

//后台时间戳转化为yyyy年MM月dd日

const long long dateTimeLong =[value longLongValue]/1000;

NSDate *dateTime = [[NSDate alloc] initWithTimeIntervalSince1970:dateTimeLong];

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];

[formatter setTimeStyle:NSDateFormatterNoStyle];

[formatter setDateStyle:NSDateFormatterMediumStyle];

NSLocale *formatterLocal = [[NSLocale alloc] initWithLocaleIdentifier:@"en_us"];

[formatter setLocale:formatterLocal];

[formatter setDateFormat:@"yyyy年MM月dd日"];

NSDate *new = [NSDate dateWithTimeInterval:0 sinceDate:dateTime];

NSString *dateString = [formatter stringFromDate:new];