NSDate零秒,没有四舍五入

Question

我想知道是否有人可以用我的方法帮助我.我有以下方法,它会将NSDate对象的秒值清零:

- (NSDate *)dateWithZeroSeconds:(NSDate *)date {
    NSTimeInterval time = round([date timeIntervalSinceReferenceDate] / 60.0) * 60.0;
    return  [NSDate dateWithTimeIntervalSinceReferenceDate:time];
}

问题是当通过日期时,例如:

2011-03-16 18:21:43 +0000

它返回:

2011-03-16 18:22:00 +0000

我不希望这种舍入发生,因为它是实际指定日期的用户,因此它需要精确到他们请求的那一刻.

任何帮助是极大的赞赏.

Answer 1

使用地板而不是圆形:

- (NSDate *)dateWithZeroSeconds:(NSDate *)date
{
    NSTimeInterval time = floor([date timeIntervalSinceReferenceDate] / 60.0) * 60.0;
    return  [NSDate dateWithTimeIntervalSinceReferenceDate:time];
}

Answer 2

使用NSCalendar和NSDateComponents获取日期的各个部分.将seconds组件设置为0,然后从该NSDateComponents创建新日期.

Answer 3

要完成,这里是使用NSCalendar和NSDateComponents引用iOS SDK 8.1的代码.

+ (NSDate *)truncateSecondsForDate:(NSDate *)fromDate;
{
     NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
     NSCalendarUnit unitFlags = NSCalendarUnitEra | NSCalendarUnitYear | NSCalendarUnitMonth |  NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute;
     NSDateComponents *fromDateComponents = [gregorian components:unitFlags fromDate:fromDate ];
     return [gregorian dateFromComponents:fromDateComponents];
}

请注意,从iOS 8开始,日历单元名称已更改.