Question

我有这个代码应该计算一个月的开始和结束日期（日期在NSPredicate中用于在CoreData商店中搜索月初和月末之间的记录）

    NSDate *startOfMonth;
    NSDate *endOfMonth;
    NSCalendar *cal = [NSCalendar currentCalendar];
    NSDate *now = [NSDate date];
    NSTimeInterval interval;

    [cal rangeOfUnit:NSMonthCalendarUnit startDate:&startOfMonth interval:&interval forDate:now];
    endOfMonth = [startOfMonth dateByAddingTimeInterval:interval-1];
    NSLog(@"\n\nstartOfMonth: %@\nendOfMonth: %@\ninterval: %f",startOfMonth, endOfMonth, interval);

这是NSLog的输出：

startOfMonth: 2014-11-01 07:00:00 +0000
endOfMonth: 2014-12-01 07:59:59 +0000
interval: 2595600.000000

如您所见， endOfMonth 不正确;它应该是2014-11-30 ......代码有什么问题？（这不是我的，我在SO上找到了它）

我更改了“cal”的timeZone属性，但仍然得到了相同的日志消息。

Answer 1

startOfMonth也打印不正确。

时间实际上是正确的，但是当你打印时，它会打印你的时区。

打印日期将在UTC时区中打印该日期。您可以在设定的时区打印，如下所示：

NSLog(@"\n\nstartOfMonth: %@\nendOfMonth: %@\ninterval: %d",[startOfMonth descriptionWithLocale:[NSLocale systemLocale]], [endOfMonth descriptionWithLocale:[NSLocale systemLocale]], (int)interval);

要更新日期，请尝试以下操作：

[cal rangeOfUnit:NSMonthCalendarUnit startDate:&startOfMonth interval:&interval forDate:now];
NSTimeInterval timeZoneOffset = [[NSTimeZone localTimeZone] secondsFromGMT];
startOfMonth = [startOfMonth dateByAddingTimeInterval:timeZoneOffset];
endOfMonth = [startOfMonth dateByAddingTimeInterval:interval-1];
NSLog(@"\n\nstartOfMonth: %@\nendOfMonth: %@\ninterval: %d",startOfMonth, endOfMonth, (int)interval);

更改日历也有效：

cal.timeZone = [NSTimeZone timeZoneWithName:@"GMT"];
[cal rangeOfUnit:NSMonthCalendarUnit startDate:&startOfMonth interval:&interval forDate:now];

Answer 2

您需要做的是将UTC转换为感兴趣的时区。

您希望将日历的timeZone属性设置为您要使用的时区。以下代码来自the Apple documentation，将时区设置为中央夏令时：

[gregorian setTimeZone:[NSTimeZone timeZoneWithAbbreviation:@"CDT"]];

Answer 3

在这里，我可以发布你想要的代码..

-(NSMutableDictionary *)getMonthsStartAndEndDatesFromDate:(NSDate *)date
{

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

    NSDateComponents *components = [gregorian components:( NSYearCalendarUnit | NSMonthCalendarUnit) fromDate:date];
    components.day = 1;

    NSDate *startDate = [[gregorian dateFromComponents:components] dateByAddingTimeInterval:0];


    NSDateComponents *components1=[gregorian components:NSMonthCalendarUnit|NSYearCalendarUnit fromDate:date];
    //NSEraCalendarUnit |
    NSInteger month=[components1 month];
    NSInteger year=[components1 year];

    if (month==12)
    {
        [components1 setYear:year+1];
        [components1 setMonth:1];
    }
    else {
        [components1 setMonth:month+1];
    }
    [components1 setDay:0];

    NSDate *endDate =[[gregorian dateFromComponents:components1] dateByAddingTimeInterval:0];


    NSMutableDictionary *dictTemp = [[NSMutableDictionary alloc] init];

    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss z"];

    startDate = [self dateFromDate:startDate WithHour:0 minute:0 second:01];
    endDate =[self dateFromDate:endDate WithHour:23 minute:59 second:59];


    NSString *StrHour = [dateFormatter stringFromDate:startDate];
    NSString *strMin = [dateFormatter stringFromDate:endDate];


    [dictTemp setObject:StrHour forKey:@"StartDate"];
    [dictTemp setObject:strMin forKey:@"EndDate"];

    return dictTemp;

}
-(NSDate *) dateFromDate:(NSDate *)date
                WithHour:(NSInteger)hour
                  minute:(NSInteger)minute
                  second:(NSInteger)second
{
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *components = [calendar components: NSYearCalendarUnit|
                                    NSMonthCalendarUnit|
                                    NSDayCalendarUnit
                                               fromDate:date];
    [components setHour:hour];
    [components setMinute:minute];
    [components setSecond:second];
    NSDate *newDate = [calendar dateFromComponents:components];
    return newDate;
}

[self getMonthsStartAndEndDatesFromDate:[NSDate new]];

此方法返回开始和结束日期像这样

EndDate =“2014-11-30 23:59:59 GMT + 5:30”; StartDate =“2014-11-01 00:01:00 GMT + 5:30”;

所以这可能对你有所帮助..

计算月份的开始日期和结束日期是不正确的

3 个答案: