CODEWITHSUNDEEP
objective-coopnsdateinstance
Jeremy Pagley
Jeremy Pagley

Reputation: 7

Instances and Calendar Error? Objective-C

This application is supposed to Log how many seconds it's been since a birthdate(1996) but when I try and log NSLog(@"It has been %f seconds since the start of 1996.", seconds); it logs:

2014-01-29 11:36:15.756 TimeAfterTime[750:303] It has been (null) seconds since the start of 1996.

my question is why does it print (null)? This is a Objective-C Command Line Tool application in Xcode. Any suggestions would be greatly appreciated! Thanks

Code I'm using:

//  main.m
//  TimeAfterTime
//
//  Created by JP on 1/28/14.
//  Copyright (c) 2014 Big Nerd Ranch. All rights reserved.
//

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[])
{

    @autoreleasepool {

        NSDateComponents *comps = [[NSDateComponents alloc] init];
        [comps setYear:1996];
        [comps setMonth:11];
        [comps setDay:7];
        [comps setHour:13];
        [comps setMinute:23];
        [comps setSecond:0];

        NSCalendar *g = [[[NSCalendar alloc] init] initWithCalendarIdentifier:NSGregorianCalendar];
        NSDate *dateOfBirth = [g dateFromComponents:comps];

        NSDate *now = [[NSDate alloc] init];
        NSLog(@"This NSDate object lives at %p", now);
        NSLog(@"The date is %@", now);

        double seconds = [now timeIntervalSinceDate:dateOfBirth];
        NSLog(@"It has been %f seconds since the start of 1996.", seconds);

    }
    return 0;
}

The result it prints in the console:

2014-01-29 11:36:15.752 TimeAfterTime[750:303] This NSDate object lives at 0x100103680
2014-01-29 11:36:15.756 TimeAfterTime[750:303] The date is 2014-01-29 16:36:15 +0000
2014-01-29 11:36:15.756 TimeAfterTime[750:303] It has been (null) seconds since the start of 1996.
Program ended with exit code: 0

Upvotes: 0

Views: 50

Answers (1)

Martin R
Martin R

Reputation: 539775

NSCalendar *g = [[[NSCalendar alloc] init] initWithCalendarIdentifier:NSGregorianCalendar];

should be

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

Due to the wrong initialization, g = nil and thus dateOfBirth = nil.

Upvotes: 3

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