通过组合两个NSDate创建一个新的NSDate

Question

我有NSDate* day1和NSDate* day2.如何NSDate* day3从第1天开始仅复制年/月/日,从第2天复制每小时/分钟/秒？

Answer 1

unsigned unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit |  NSDayCalendarUnit;
NSDateComponents *comps = [[NSCalendar currentCalendar] components:unitFlags fromDate:day1];
NSDate *day3 = [[NSCalendar currentCalendar] dateFromComponents:comps];

unitFlags = NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;
comps = [[NSCalendar currentCalendar] components:unitFlags fromDate:day2];
day3 = [[NSCalendar currentCalendar] dateByAddingComponents:comps toDate:day3 options:0];

资料来源:

1. NSDateComponents类参考
2. NSCalendar类参考