我怎么能得到一个NSDate对象的年/月/日,没有其他信息?我意识到我可以用类似这样的东西来做这件事:

NSCalendar *cal = [[NSCalendar alloc] init];
NSDateComponents *components = [cal components:0 fromDate:date];
int year = [components year];
int month = [components month];
int day = [components day];

但是对于像获取NSDate的年/月/日这样简单的事情来说,这似乎是一大堆麻烦。还有其他解决办法吗?


当前回答

试试这个……

代码片段:

 NSDateComponents *components = [[NSCalendar currentCalendar] components:NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear fromDate:[NSDate date]];
 int year = [components year];
 int month = [components month];
 int day = [components day];

它给出了当前的年、月、日

其他回答

因为这显然是我最喜欢的答案,我将试着编辑它,以包含更多的信息。

Despite its name, NSDate in and of itself simply marks a point in machine time, not a date. There's no correlation between the point in time specified by an NSDate and a year, month, or day. For that, you have to refer to a calendar. Any given point in time will return different date information based on what calendar you're looking at (dates are not the same in both the Gregorian and Jewish calendars, for instance), and while the Gregorian calendar is the most widely used calendar in the world - I'm assuming - we're a little biased that NSDate should always use it. NSDate, luckily, is far more bipartisan.


获取日期和时间将必须通过NSCalendar,正如你提到的,但有一个更简单的方法来做它:

NSDateComponents *components = [[NSCalendar currentCalendar] components:NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear fromDate:[NSDate date]];

它生成一个NSDateComponents对象,其中包含来自当前系统日历的日、月和年。(注意:这不一定是当前用户指定的日历,只是默认的系统日历。)

当然,如果你使用不同的日历或日期,你可以很容易地更改它。可用日历和日历单元的列表可以在NSCalendar类引用中找到。更多关于NSDateComponents的信息可以在NSDateComponents类参考中找到。


作为参考,从NSDateComponents中访问单个组件相当简单:

NSInteger day = [components day];
NSInteger month = [components month];
NSInteger year = [components year];

You just have to be mindful: NSDateComponents won't contain valid information for any fields you ask for unless you generated them with that valid information (i.e. request NSCalendar to provide that information with NSCalendarUnits). NSDateComponents contain no reference information in and of themselves - they're just simple structures that hold numbers for you to access. If you want to also get an era, for instance, out of NSDateComponents, you'll have to feed the generator method from NSCalendar with the NSCalendarUnitEra flag.

要获得人类可读的字符串(日,月,年),你可以这样做:

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateStyle:NSDateFormatterMediumStyle];
NSString *string = [dateFormatter stringFromDate:dateEndDate];

我这样做....

NSDate * mydate = [NSDate date];

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

NSCalendarUnit units = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay;

NSDateComponents * myComponents  = [mycalendar components:units fromDate:mydate];

NSLog(@"%d-%d-%d",myComponents.day,myComponents.month,myComponents.year);

快2.倍

extension NSDate {
    func currentDateInDayMonthYear() -> String {
        let dateFormatter = NSDateFormatter()
        dateFormatter.dateFormat = "d LLLL yyyy"
        return dateFormatter.stringFromDate(self)
    }
}

你可以用它作为

NSDate().currentDateInDayMonthYear()

输出

6 March 2016

从iOS 8.0(和OS X 10)开始,你可以使用component方法来简化获取单个日期组件,如下所示:

int year = [[NSCalendar currentCalendar] component:NSCalendarUnitYear fromDate:[NSDate date]];

应该使事情更简单,希望这是有效地实施。