获取一个月的最后一天答案

【问题标题】：Getting the last day of a month获取一个月的最后一天
【发布时间】：2010-05-05 10:28:06
【问题描述】：

如何以NSDate 获取当月的最后一天？

【问题讨论】：

重复？ stackoverflow.com/questions/1731322/…
它不是一个精确的副本。
现在这很容易： stackoverflow.com/a/45150320/294884

标签： objective-c cocoa-touch cocoa date nsdate

【解决方案1】：

NSDate *curDate = [NSDate date];
NSCalendar* calendar = [NSCalendar currentCalendar];
NSDateComponents* comps = [calendar components:NSYearCalendarUnit|NSMonthCalendarUnit|NSWeekCalendarUnit|NSWeekdayCalendarUnit fromDate:curDate]; // Get necessary date components

// set last of month
[comps setMonth:[comps month]+1];
[comps setDay:0];
NSDate *tDateMonth = [calendar dateFromComponents:comps];
NSLog(@"%@", tDateMonth);

应该也可以。

【讨论】：

但是为什么 day = 0 会给出上个月的最后日期？
这就是为什么月份 + 1 存在的原因，Raj

【解决方案2】：

// Adapted from running code in my app

NSDate *curDate = [NSDate date];
NSCalendar *currentCalendar = [NSCalendar currentCalendar];
NSRange daysRange = 
[currentCalendar 
 rangeOfUnit:NSDayCalendarUnit 
 inUnit:NSMonthCalendarUnit 
 forDate:curDate];

// daysRange.length will contain the number of the last day
// of the month containing curDate

NSLog(@"%i", daysRange.length);

【讨论】：

对于那些痴迷于单线的人：P days = [NSCalendar.currentCalendar rangeOfUnit:NSDayCalendarUnit inUnit:NSMonthCalendarUnit forDate:myDate].length

【解决方案3】：

把它放在一个类别中：

-(NSDate*)lastDayOfMonth
{
    NSInteger dayCount = [self numberOfDaysInMonthCount];

    NSDateComponents *comp = [[self calendar] components:
                              NSCalendarUnitYear |
                              NSCalendarUnitMonth |
                              NSCalendarUnitDay fromDate:self];

    [comp setDay:dayCount];

    return [[self calendar] dateFromComponents:comp];
}

-(NSInteger)numberOfDaysInMonthCount
{
    NSRange dayRange = [[self calendar] rangeOfUnit:NSCalendarUnitDay
                                             inUnit:NSCalendarUnitMonth
                                            forDate:self];

    return dayRange.length;
}

-(NSCalendar*)calendar
{
    NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];    
    [calendar setTimeZone:[NSTimeZone timeZoneWithName:TIMEZONE]];
    return calendar;
}

【讨论】：

我正在使用与此类似的东西，谢谢，但是您为什么使用 NSGregorianCalendar 而不是 [NSCalendar currentCalendar]？
当前日历可能不是 NSGregorian 日历，当时我想明确表示一下。
如果你想要当月最后一天的最后一秒，只需添加 comp.hour = 24; comp.minute = 0; comp.second = 0;

【解决方案4】：

斯威夫特版本

extension NSDate {
    func lastDayOfMonth() -> NSDate {
        let calendar = NSCalendar.currentCalendar()
        let dayRange = calendar.rangeOfUnit(.Day, inUnit: .Month, forDate: self)
        let dayCount = dayRange.length
        let comp = calendar.components([.Year, .Month, .Day], fromDate: self)

        comp.day = dayCount

        return calendar.dateFromComponents(comp)!
    }
}

【讨论】：

【解决方案5】：

iOS 7 版本

只是为了摆脱弃用......在一天的最后一秒添加了一点点。

    // current date
    NSDate *now = [NSDate new];

    // get last day of the current month
    NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
    [calendar setTimeZone:[NSTimeZone systemTimeZone]];

    NSRange dayRange = [ calendar rangeOfUnit:NSCalendarUnitDay
                                       inUnit:NSCalendarUnitMonth
                                      forDate:now];

    NSInteger numberOfDaysInCurrentMonth = dayRange.length;

    NSDateComponents *comp = [calendar components:
                              NSCalendarUnitYear |
                              NSCalendarUnitMonth |
                              NSCalendarUnitDay fromDate:now];

    comp.day = numberOfDaysInCurrentMonth;
    comp.hour = 24;
    comp.minute = 0;
    comp.second = 0;

    NSDate *endOfMonth = [calendar dateFromComponents:comp];

【讨论】：

【解决方案6】：

Swift 3.0.1 版本

extension Date {
func lastDayOfMonth() -> Date {
    let calendar = NSCalendar.current
    let dayRange = calendar.range(of: .day, in: .month, for: self)
    let dayCount = dayRange?.count
    var comp = calendar.dateComponents([.year, .month, .day], from: self)
    comp.day = dayCount
    return calendar.date(from: comp)!
    }
}

【讨论】：

【解决方案7】：

使用 Swift 3 和 iOS 10，我发现最简单的方法是 Calendar's dateInterval(of:for:)：

func monthInterval() -> DateInterval? {
    let calendar = Calendar.current
    guard let interval = calendar.dateInterval(of: .month, for: Date()) else { return nil }
    let duration = interval.duration
    // Subtract one second because dateInterval(of:for:)'s end date returns the beginning of the following month
    return DateInterval(start: interval.start, duration: duration - 1)
}

guard let interval = monthInterval() else { return }

然后您可以使用interval.start 和interval.end 来获取您需要的日期。

【讨论】：

【解决方案8】：

NSDate *curDate = [NSDate date];
        NSCalendar *currentCalendar = [NSCalendar currentCalendar];
        NSRange daysRange = [[NSCalendar currentCalendar] rangeOfUnit:NSCalendarUnitDay inUnit:NSCalendarUnitMonth
         forDate:curDate];
        NSDateComponents* comps = [currentCalendar components:NSCalendarUnitYear|NSCalendarUnitMonth|NSCalendarUnitDay fromDate:curDate];
        [comps setDay:daysRange.length];
        NSDate *maximumDate = [[NSCalendar currentCalendar] dateFromComponents:comps];

【讨论】：

【解决方案9】：

变通功能：

-(int)GetLastDayOfMonth:(NSDate *)date
{
    int last_day = 27;
    NSCalendar *cal=[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSDateComponents *compsMonth = [cal components:NSWeekdayCalendarUnit | NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit fromDate:date];
    [compsMonth setDay:last_day];
    int month = [compsMonth month]; 
    while(TRUE){
        [compsMonth setDay:last_day+1];
        NSDate *dateFuture = [cal dateFromComponents:compsMonth];
        NSDateComponents *futureComps = [cal components:NSWeekdayCalendarUnit | NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit fromDate:dateFuture];
        if(month != [futureComps month]){
            return last_day;
        }
        last_day+=1;
    }
    return last_day;
}

【讨论】：

不需要循环