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从NSCalendar获得一个月的第一天

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7

我有一个方法的子集，需要获得当月的第一天 .

NSDate *today = [NSDate date];  // returns correctly 28 february 2013
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *components = [[NSDateComponents alloc] init];
components.day = 1;
NSDate *dayOneInCurrentMonth = [gregorian dateByAddingComponents:components toDate:today options:0];

dayOneInCurrentMonth 然后打印 2013-03-01 09:53:49 +0000 ，即下个月的第一天 .

我如何获得当月的第一天？

cocoa cocoa-touch calendar nscalendar nsdatecomponents

6 回答

  • 1

    你的逻辑是错误的：你没有将日期设置为1，而是在当前日期添加一天 .

    尝试类似的东西：

    NSDate *today = [NSDate date];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];

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

NSDate *dayOneInCurrentMonth = [gregorian dateFromComponents:components];
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  • 16

    你想要 [NSCalender dateFromComponents:] ：

    NSDate *dayOneInCurrentMonth = [gregorian dateFromComponents:components];
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  • 1

    从给定日期到第一个的简单方法：

    NSDate *first = [gregorian dateBySettingUnit:NSCalendarUnitDay value:1 ofDate:date options:0];
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  • 1

    获取上个月第一个和最后一个日期的简便方法是：

    NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDateComponents *comp = [gregorian components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay ) fromDate:[NSDate date]];

//TO GET PREVIOUS MONTH LAST DAY
[comp setMonth:[comp month]];
[comp setDay:1];
NSDate *tDateMonth = [gregorian dateFromComponents:comp];
NSLog(@"LAST DAY OF PREVIOUS MONTH ;  %@", tDateMonth);

//TO GET PREVIOUS MONTH FIRST DAY
[comp setMonth:[comp month]-1];
[comp setDay:3];
NSDate *td = [gregorian dateFromComponents:comp];
NSLog(@"FIRST DAY OF PREVIOUS MONTH ;  %@", td);

    希望这可以帮助

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  • 0

    通过创建新变量对内存使用来说代价很高，最好使用日期格式化程序来获取当月的第一天

    today = [NSDate date];

firstDayDateFormatter = [[NSDateFormatter alloc] init];
[firstDayDateFormatter setDateFormat:@"01-MM-yyyy"];
dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"dd-MM-yyyy"];
[dateFormatter setLocale:[NSLocale localeWithLocaleIdentifier:@"en_US"]];
firstDayOfTheMonth = [mdfDateFormat dateFromString:[firstDayDateFormatter stringFromDate:today]];
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  • 0
    NSDate *startDate = nil;
[[NSCalendar currentCalendar] rangeOfUnit:NSCalendarUnitMonth startDate:&startDate interval:NULL forDate:date];

return startDate;
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