EXC_BAD_ACCESS when trying to create a new NSDictionary

Question

I'm having troubles with creating NSDictionaries in a loop and adding it to an NSMutableArray.

Basically I just want to change the names of the keys, but since I couldn't find a function for that I went for following code:

- (NSMutableArray *)getCategoriesForChannel:(int)channelId {
    NSDictionary *data = [self call:@"get_categories.ashx"];
    NSArray *categories = [data objectForKey:@"categories"];
    NSMutableArray *returnArray = [NSMutableArray
                          arrayWithCapacity:[categories count]];

    for(NSDictionary *category in categories) {
        [returnArray addObject:[NSDictionary dictionaryWithObjectsAndKeys:
                         [category objectForKey:@"Channel_id"], @"id",
                         [category objectForKey:@"Channel_name"], "@name", nil]];
    }
    return returnArray;
}

But app always quits when it reaches the addObject: method and throws an EXC_BAD_ACCESS. I think that it has got something to do with memory management, but since I don't really have a C-background I have no idea how to solve this issue. Can someone please point me to the right direction? Thanks in advance!

NSGod · Accepted Answer · 2013-01-17T17:50:54.543

29

[returnArray addObject:
    [NSDictionary dictionaryWithObjectsAndKeys:
    [category objectForKey:@"Channel_id"], @"id",
    [category objectForKey:@"Channel_name"], "@name", nil]];

If this is in fact the code you have (and the typo wasn't introduced while writing it in your web browser), notice that the last key you have is "@name" instead of @"name". That would effectively be a C-string, rather than an NSString, which can't properly be added into an NSArray (or most collection classes, for that matter).

edited Jan 17 '13 at 17:50

answered Dec 11 '10 at 17:28

NSGod

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1

Thank you sir, that was in fact the problem! – Lucas G Dec 13 '10 at 06:20
1

Sometimes another set of eyes is all you need! This saved me what I'm sure would have been hours of frustration. Thanks. – MikeCocoa Dec 19 '12 at 19:38
3

Arg, just made the same mistake ;-( unbelivable there is no compilation warning .... – Thomas Decaux Apr 30 '13 at 13:30
1

Oh God. This seems to be a very common stuff - faced it and was frustrated with myself!! Thanks. – Gurusharan S Sep 26 '14 at 03:12

score 2 · Answer 2 · answered Dec 11 '10 at 17:07

2

Within the loop can you NSLog this [category objectForKey:@"Channel_id"] and [category objectForKey:@"Channel_name"]? I suspect one is giving nil and causing the trouble. Not sure. Just a guess.

answered Dec 11 '10 at 17:07

hol

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EXC_BAD_ACCESS when trying to create a new NSDictionary

2 Answers2