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

NSString *dateString = [dateFormatter stringFromDate:[NSDate date]];
NSLog(@"%@",dateString);


// Retrieve NSDate instance from stringified date presentation
NSDate *dateFromString = [dateFormatter dateFromString:dateString];

// Create and initialize date component instance
NSDateComponents *dateComponents = [[NSDateComponents alloc] init];
[dateComponents setDay:2];

// Retrieve date with increased days count
NSDate *newDate = [[NSCalendar currentCalendar]
                   dateByAddingComponents:dateComponents
                   toDate:dateFromString options:0];

NSLog(@"Original date: %@", [dateFormatter stringFromDate:dateFromString]);
NSLog(@"New date: %@", [dateFormatter stringFromDate:newDate]);

出力

   2013-05-17
   Original date: 2013-05-17
    New date: 1412647-09-06

それに2日足します。新しい日付は「2013-05-19?」のはずです。何が間違っているのか教えてもらえますか?よろしくお願いします。

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2 に答える 2

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のinitメソッドはNSDateComponents、コンポーネントを初期化しません。したがって、たとえば、年は定義されていません。フォーム Apple のドキュメント:

An instance of NSDateComponents is not responsible for answering questions about a date beyond the 
information with which it was initialized. For example, if you initialize one with May 6, 2004,   
its weekday is NSUndefinedDateComponent
于 2013-05-17T11:33:40.923 に答える