iphone - 将日期和时间合并到单个NSDate中时出现问题

我正在尝试通过这种方法将一个NSDate的时间值(小时，分钟，秒)与第二个NSDate的日期值(天，月，年)结合起来:

+ (NSDate *)combineDate:(NSDate *)date withTime:(NSDate *)time {

    NSCalendar *gregorian = [[NSCalendar alloc]
        initWithCalendarIdentifier:NSGregorianCalendar];

    NSDateComponents *dateComponents = [gregorian components:(NSDayCalendarUnit |
        NSWeekdayCalendarUnit) fromDate:date];
    NSDateComponents *timeComponents = [gregorian components:(NSDayCalendarUnit |
        NSWeekdayCalendarUnit) fromDate:time];

    NSDateComponents *comp = [NSDateComponents alloc];
    [comp setSecond:[timeComponents second]];
    [comp setHour:[timeComponents hour]];
    [comp setMinute:[timeComponents minute]];
    [comp setYear:[dateComponents year]];
    [comp setMonth:[dateComponents month]];
    [comp setDay:[dateComponents day]];

    NSDate *combDate = [gregorian dateFromComponents:comp];

    [gregorian release];
    [comp release];

    return combDate;
}

...但是返回的实际上是乱码(例如，年份以“1”表示)。有人看到这种方法有什么问题吗？

最佳答案

我使用了错误的日历组件。这是更正后的功能(现在适用于ARC):

+ (NSDate *)combineDate:(NSDate *)date withTime:(NSDate *)time {

    NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:
        NSGregorianCalendar];

    unsigned unitFlagsDate = NSYearCalendarUnit | NSMonthCalendarUnit
        |  NSDayCalendarUnit;
    NSDateComponents *dateComponents = [gregorian components:unitFlagsDate
        fromDate:date];
    unsigned unitFlagsTime = NSHourCalendarUnit | NSMinuteCalendarUnit
        |  NSSecondCalendarUnit;
    NSDateComponents *timeComponents = [gregorian components:unitFlagsTime
        fromDate:time];

    [dateComponents setSecond:[timeComponents second]];
    [dateComponents setHour:[timeComponents hour]];
    [dateComponents setMinute:[timeComponents minute]];

    NSDate *combDate = [gregorian dateFromComponents:dateComponents];

    return combDate;
}