NSCalendar method with selector descriptionWithCalendarFormat error

Question

I get the below error from my code:

/Users/user/Dropbox/dev/bignerdranch_cocoa/lottery/LotteryEntry.m:43:16: error: receiver type 'NSCalendar' for instance message does not declare a method with selector 'descriptionWithCalendarFormat:' [4]

Code:

//
//  LotteryEntry.m
//  lottery
//
//  Created by user on 11/7/11.
//  Copyright (c) 2011 __MyCompanyName__. All rights reserved.
//

#import "LotteryEntry.h"

@implementation LotteryEntry

- (void) prepareRandomNumbers
{
    firstNumber = random() % 100 + 1;
    secondNumber = random() % 100 + 1;
}

- (void) setEntryDate:(NSCalendarDate *)date
{
    entryDate = date;
}

- (NSCalendarDate *) entryDate
{
    return entryDate;
}

- (int)firstNumber
{
    return firstNumber;
}

- (int)secondNumber
{
    return secondNumber;
}

- (NSString *)description
{
    NSString *result;
    result = [[NSString alloc] initWithFormat:@"%@ = %d and %d", 
              [entryDate descriptionWithCalendarFormat:@"%b %d %Y"],
              firstNumber, secondNumber;
}
@end

Answer 1

Because the method descriptionWithCalendarFormat is on NSDate, not NSCalendar.