一些考虑语言环境设置等的 NSDate 问题
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【中文标题】一些考虑语言环境设置等的 NSDate 问题【英文标题】：Some NSDate questions considering locale settings etc 【发布时间】：2014-02-16 13:31:17 【问题描述】：我对 ios 还是有点陌生，并且在使用 NSDate 时遇到了一些困难。基本上我的应用中有特定的 CostPeriods：
CostPeriodDaily
CostPeriodWeekly
CostPeriodMonthly
CostPeriodSemiAnnually
CostPeriodAnnually
根据 CostPeriod，我想要那个特定时期的开始和结束日期。 CostPeriodDaily 当然是从（即今天）2014 年 2 月 16 日 00:00:00（当地时间）- 2014 年 2 月 16 日 23:59:59（当地时间）。每月将从 2014 年 2 月 1 日 00:00:00 到 2014 年 2 月 28 日 23:59:59 等。
我首先有两个具体问题：
-
NSWeekdayCalendarUnit：1 总是星期日和 7 星期六？不管
设置了什么语言环境？
如果我 NSLog 我的 endDate（如下面的代码）或开始日期，它通常是日期和 23:00:00，因为我生活在时区
格林威治标准时间+1。这是正确的吗？
现在到我的 endDate 函数，还有两个问题:-)
这个功能一般可以吗？或者我会根据特定的语言环境设置出现一些问题？ 我的 CostPeriodWeekly 案例给了我今天的错误日期 2014-02-15 23:00:00 +0000。我不知道为什么...？+(NSDate *)endDateForCurrentCostPeriod:(CostPeriod)costPeriod NSCalendar *gregorian = [[NSCalendar 分配] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *todayComponents =
[gregorian components:(NSDayCalendarUnit | NSWeekdayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit ) fromDate:[NSDate date]];
NSRange daysOfCurrentMonth = [gregorian rangeOfUnit:NSDayCalendarUnit inUnit:NSMonthCalendarUnit forDate:[NSDate date]];
NSDateComponents *endDateComponents = [[NSDateComponents alloc] init];
switch (costPeriod)
case CostPeriodDaily:
[endDateComponents setDay:[todayComponents day]];
[endDateComponents setMonth:[todayComponents month]];
[endDateComponents setYear:[todayComponents year]];
break;
case CostPeriodWeekly:
//Weekday 1 = sunday, 2 = monday
if([todayComponents weekday] == 1)
//Sunday -> do nothing, we have the end date
[endDateComponents setDay:[todayComponents day]];
[endDateComponents setMonth:[todayComponents month]];
[endDateComponents setYear:[todayComponents year]];
else
// all other days of current week, so 8- weekday (if Friday: 8 - 6 = + 2 -> Sunday)
NSDateComponents *componentsToAdd = [[NSDateComponents alloc] init];
[componentsToAdd setDay: 8 - [todayComponents weekday]];
NSDate *endOfWeek = [gregorian dateByAddingComponents:componentsToAdd
toDate:[NSDate date] options:0];
NSDateComponents *endOfWeekComponents = [gregorian components:(NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit) fromDate:endOfWeek];
[endDateComponents setDay:[endOfWeekComponents day]];
[endDateComponents setMonth:[endOfWeekComponents month]];
[endDateComponents setYear:[endOfWeekComponents year]];
break;
case CostPeriodMonthly:
[endDateComponents setDay:daysOfCurrentMonth.length];
[endDateComponents setMonth:[todayComponents month]];
[endDateComponents setYear:[todayComponents year]];
break;
case CostPeriodSemiAnnually:
[endDateComponents setYear:[todayComponents year]];
if([todayComponents month] <= 6)
[endDateComponents setDay:30];
[endDateComponents setMonth:6];
else
[endDateComponents setDay:31];
[endDateComponents setMonth:12];
break;
case CostPeriodAnnually:
[endDateComponents setDay:31];
[endDateComponents setMonth:12];
[endDateComponents setYear:[todayComponents year]];
break;
default:
[endDateComponents setDay:daysOfCurrentMonth.length];
[endDateComponents setMonth:[todayComponents month]];
[endDateComponents setYear:[todayComponents year]];
break;
NSDate *endDate = [gregorian dateFromComponents:endDateComponents];
return endDate;
【问题讨论】：
【参考方案1】：NSWeekdayCalendarUnit：1 总是星期日和 7 星期六？无论设置什么语言环境？
没错。但这并不意味着 1=Sunday 总是被认为是一周中的第一天。 NSCalendar 有一个 firstWeekDay 方法，那个
取决于语言环境。 （例如，在德国，星期一是一周的第一天。）
如果我 NSLog 我的 endDate（如下代码所示）或开始日期 通常是日期和 23:00:00，因为我住在时区 格林威治标准时间+1。这是正确的吗？
没错。
这个功能一般都可以吗，或者我会在一些问题中运行 取决于特定的区域设置？
您的方法看起来过于复杂。要确定您可以使用的时间段
NSDate *now = [NSDate date];
NSCalendar *cal = [NSCalendar currentCalendar];
NSDate *startOfPeriod, *endOfPeriod;
NSTimeInterval lengthOfPeriod;
NSCalendarUnit unit = NSDayCalendarUnit; // or NSWeekCalendarUnit, NSMonthCalendarUnit, ...
[cal rangeOfUnit:unit startDate:&startOfPeriod interval:&lengthOfPeriod forDate:now];
endOfPeriod = [startOfPeriod dateByAddingTimeInterval:lengthOfPeriod]
根据您的语言环境，这应该可以正常工作。对于今天的当前一周 （2 月 16 日星期日）在德国会给出结果
startOfPeriod = 2014-02-10 00:00:00 CET
endOfPeriod = 2014-02-17 00:00:00 CET
因为这里的一周从星期一开始。 （所以实际上endOfPeriod并不是结束
期间的开始，但下一个期间的开始。）
半年期
没有对应的NSCalendarUnit，可以这样处理：
NSDate *now = [NSDate date];
NSCalendar *cal = [NSCalendar currentCalendar];
// Compute start and end of the current year (as above):
NSDate *startOfYear, *endOfYear;
NSTimeInterval lengthOfYear;
NSCalendarUnit unit = NSYearCalendarUnit;
[cal rangeOfUnit:unit startDate:&startOfYear interval:&lengthOfYear forDate:now];
endOfYear = [startOfYear dateByAddingTimeInterval:lengthOfYear];
// Compute middle of the year:
NSDateComponents *halfYear = [[NSDateComponents alloc] init];
NSRange range = [cal rangeOfUnit:NSMonthCalendarUnit inUnit:NSYearCalendarUnit forDate:now];
halfYear.month = range.length/2;
NSDate *middleOfYear = [cal dateByAddingComponents:halfYear toDate:startOfYear options:0];
// Compare current date with middle of the year and set start/end of period:
NSDate *startOfPeriod, *endOfPeriod;
if ([now compare:middleOfYear] == NSOrderedAscending)
startOfPeriod = startOfYear;
endOfPeriod = middleOfYear;
else
startOfPeriod = middleOfYear;
endOfPeriod = endOfYear;
编辑：在 Martin 的帮助下改变了一切。有效，但仍然对结束日期 +1 天 +1 小时的必要性感到困惑......
+ (NSDate *)startDateForCostPeriod:(CostPeriod)costPeriod withDate:(NSDate *)date
NSCalendar *calender = [NSCalendar currentCalendar];
NSDate *startOfPeriod;
NSTimeInterval lengthOfPeriod;
//If unit is not initialized here, semi annual throws always a caution message since no unit is initialized there
NSCalendarUnit unit = NSMonthCalendarUnit;
//For the SemiAnnual period we need date components
NSDateComponents *todayComponents =
[calender components:(NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit ) fromDate:date];
NSDateComponents *startDateComponents = [[NSDateComponents alloc] init];
switch (costPeriod)
case CostPeriodDaily:
unit = NSDayCalendarUnit;
break;
case CostPeriodWeekly:
unit = NSWeekCalendarUnit;
break;
case CostPeriodMonthly:
unit = NSMonthCalendarUnit;
break;
case CostPeriodSemiAnnually:
[startDateComponents setDay:1];
[startDateComponents setYear:[todayComponents year]];
if([todayComponents month] <= 6)
[startDateComponents setMonth:1];
else
[startDateComponents setMonth:7];
break;
case CostPeriodAnnually:
unit = NSYearCalendarUnit;
break;
default:
unit = NSMonthCalendarUnit;
break;
if(costPeriod != CostPeriodSemiAnnually)
[calender rangeOfUnit:unit startDate:&startOfPeriod interval:&lengthOfPeriod forDate:date];
return startOfPeriod;
else
return [calender dateFromComponents:startDateComponents];
+ (NSDate *)endDateForCostPeriod:(CostPeriod)costPeriod withDate:(NSDate *)date
NSCalendar *calender = [NSCalendar currentCalendar];
NSDate *startOfPeriod;
NSTimeInterval lengthOfPeriod;
//If unit is not initialized here, semi annual throws always a caution message since no unit is initialized there
NSCalendarUnit unit = NSMonthCalendarUnit;
//For the SemiAnnual period we need date components
NSDateComponents *todayComponents =
[calender components:(NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit ) fromDate:date];
NSDateComponents *endDateComponents = [[NSDateComponents alloc] init];
switch (costPeriod)
case CostPeriodDaily:
unit = NSDayCalendarUnit;
break;
case CostPeriodWeekly:
unit = NSWeekCalendarUnit;
break;
case CostPeriodMonthly:
unit = NSMonthCalendarUnit;
break;
case CostPeriodSemiAnnually:
[endDateComponents setYear:[todayComponents year]];
if([todayComponents month] <= 6)
[endDateComponents setDay:30];
[endDateComponents setMonth:6];
else
[endDateComponents setDay:31];
[endDateComponents setMonth:12];
break;
case CostPeriodAnnually:
unit = NSYearCalendarUnit;
break;
default:
unit = NSMonthCalendarUnit;
break;
if(costPeriod != CostPeriodSemiAnnually)
[calender rangeOfUnit:unit startDate:&startOfPeriod interval:&lengthOfPeriod forDate:date];
return [startOfPeriod dateByAddingTimeInterval:lengthOfPeriod];
else
//somehow if you take the date without a time it is always 1 day and 1 hour before. i.e. 16.2.2014 is 15.2.2014 22:00:00
//thats why you need to add 1 day and 1 hour!
NSDate *endDate = [calender dateFromComponents:endDateComponents];
NSDateComponents *componentsToAdd = [[NSDateComponents alloc] init];
[componentsToAdd setDay: 1];
[componentsToAdd setHour: 1];
endDate = [calender dateByAddingComponents:componentsToAdd
toDate:endDate options:0];
return endDate;
【讨论】：
非常感谢马丁。如果我理解正确，您的这种方法适用于每个地区，无论星期一还是星期日是一周的第一天，无论什么时区等？你能告诉我你是如何用这种方法得到一个时期的开始日期的吗？ @MichiZH：开始日期已经用那个代码计算出来了。它在startDate:&startOfPeriod 参数中有点“隐藏”。是的，这应该会根据您的语言环境和时区给出正确的结果。
再次感谢您。现在将在我的应用程序中尝试 :-) 总是很高兴学到一些东西 :-)
还有一个问题：半年期间你会使用什么单位和lengthOfPeriod？
@MichiZH：半年没有日历单位。对于这种情况，您必须使用 NSDateComponents 计算它。以上是关于一些考虑语言环境设置等的 NSDate 问题的主要内容，如果未能解决你的问题，请参考以下文章