时间解析(NSDate、NSCalendar、NSDateComponents)：
1、使用NSCalendar和NSDateComponents解析日期，直接获取到年月日时分秒。获取到年月日时分秒其实都是通过NSDateComponents来解析的
[calendar components:(NSCalendarUnitYear |NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:date]；
NSDate *date = [NSDate date];
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *comps;
// 年月日获得
comps = [calendar components:(NSCalendarUnitYear |NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:date];
NSInteger y = [comps year];
NSInteger m = [comps month];
NSInteger d = [comps day];
NSLog(@"year: %ld month: %ld, day: %ld", y, m, d);
//当前的时分秒获得 comps = [calendar components:(NSCalendarUnitHour |NSCalendarUnitMinute | NSCalendarUnitSecond) fromDate:date]; NSInteger h = [comps hour]; NSInteger m = [comps minute]; NSInteger s = [comps second]; NSLog(@"hour: %li minute: %li second: %li", h, m,s);
2、还可以使用NSDateFormatter将日期格式化为 "yyyy-MM-dd hh/HH:mm:ss" 后，再用字符串逐步切割，逐渐获取到年月日时分秒（先用" "切割，然后再用”-“和”:"切割）即可获取到
NSDate *date = [NSDate date]; NSDateFormatter *formatter= [[NSDateFormatteralloc] init]; formatter.dateFormat =@"yyyy-MM-dd HH:mm:ss"; NSString *str = [formatterstringFromDate:date]; NSArray *arr = [str componentsSeparatedByString:@" "]; NSArray *arr1 = [arr[0] componentsSeparatedByString:@"-"]; // 年 月 日 NSArray *arr2 = [arr[1] componentsSeparatedByString:@":"]; // 时 分 秒
iOS NSDate、NSCalendar、NSDateComponents
原文：http://www.cnblogs.com/snowcoming/p/5379928.html