Why is my object nil when I get it from a NSMutableArray?

Question

I'm having a problem with this code here

Book *theNewBook = [self parseTheBookXML];
// The book is not nil here
NSLog(@"The book's title: %@, number of pages:%@ and author: %@",theNewBook.title, theNewBook.pages, theNewBook.author);

[_theBooksArray addObject:theNewBook];

// TEST
Book *testBook = [_theBooksArray objectAtIndex:0];
// The book is nil here
NSLog(@"The book's title: %@, number of pages:%@ and author: %@",testBook.title, testBook.pages, testBook.author);

Can anyone tell me why my book object is 'nil' because I've hit a wall over here...

Thanks, sry for the stupid question. The array was never initialized alright...:/ — Groot, Jan 24 '13 at 13:24
Best way to check stuff like this always is to Log you Array: NSLog(@"Array: %@",_theBooksArray); — pmk, Jan 24 '13 at 13:26
@Filip : you can write your answer here in Answer section :) — Anoop Vaidya, Jan 24 '13 at 13:27
@Filip Or don't bother as it's been seen thousands of times before. — trojanfoe, Jan 24 '13 at 13:28
I hate when that happens - forgot to initialize something - I wish future programming languages will initialize the variable for you before hand. If I define a array you bet I wanna use it so ... initialize it by default! — Sam B, Jan 24 '13 at 17:22
possible duplicate of [Having trouble adding objects to NSMutableArray in Objective C](http://stackoverflow.com/questions/851926/having-trouble-adding-objects-to-nsmutablearray-in-objective-c) — jscs, Jan 25 '13 at 02:32

score 1 · Accepted Answer · edited Jan 24 '13 at 14:58

1

As you can see from the comments on my question my problem was that I had not initialized the array I was accessing. So INSTEAD of

[_theBooksArray addObject:theNewBook];

calling

_theBooksArray = [[NSMutableArray alloc] initWithObjects:theNewBook, nil];

will do the trick.

edited Jan 24 '13 at 14:58

Mick MacCallum

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answered Jan 24 '13 at 14:09

Groot

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score 0 · Answer 2 · edited Jan 24 '13 at 14:58

0

[_theBooksArray addObject:theNewBook];
[_theBooksArray count];

print the log and check the array count.

edited Jan 24 '13 at 14:58

Mick MacCallum

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answered Jan 24 '13 at 13:26

Saurabh Shukla

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The OP already solved the problem by checking if the array was initialized. – David Rönnqvist Jan 24 '13 at 13:27
@AKV At the time of writing, he has 2 downvotes and 1 upvote, so he would lose 6 points if he deleted his answer. – trojanfoe Jan 24 '13 at 14:29
@trojanfoe :p I like downvotes more than up votes, but there should a comment with that. from past 15 days.... i m gettng downvotes without any comment. Even I cant know who is downvoting me 3-5 times everyday. :( – Anoop Vaidya Jan 24 '13 at 17:19

score 0 · Answer 3 · answered Jan 25 '13 at 07:20

0

You Must Init The Array Before Using it.

_theBooksArray = [[NSMutableArray alloc] init];

answered Jan 25 '13 at 07:20

Hmeedo

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Why is my object nil when I get it from a NSMutableArray?

3 Answers3