Programme crashes when add dictionary to array?

Question

I have a crash problem when I am trying to add object into array, I think I have problem with the way i create object and release it. But I am not quite sure cause I am still kinda weak with memory management

 NSMutableDictionary *schools = [[NSMutableDictionary alloc] init];
    [schools setObject:name forKey:kFavoriteSchoolName];
    //load data is getting data from NSUserDefault which I save
    NSMutableArray *loadedArray = [self loadData];

//if loadedarray has object in there, then continue adding schools to it or make new array
if([loadedArray count] > 0)
{
    [loadedArray addObject:schools];

    > // it crashes here


    [schools release];

    return loadedArray;
} else
{ 

    //It will add the school to the array for the first time if there is nothing when it loaded.

    NSMutableArray *tempArray = [[[NSMutableArray alloc] init] autorelease];
    [tempArray addObject:schools];

    [schools release];

    return tempArray;
}

This function help add the school into favorite list. I cant add once, but it crashes when I add it again.

This is my code of loadData function

- (NSMutableArray *) loadData
{
    NSUserDefaults *userDefault = [NSUserDefaults standardUserDefaults];
    
    NSMutableArray *list = [userDefault objectForKey:kSchoolList];
    
    return list;
    
}

The log does not say anything but this: Thread 1: Program received signal "SGABRT"

when I first run the programme and add, it is fine, I add school again then only it crashes, crashes at [loadedArray addobject:schools];

NSMutableArray *loadedArray = [self loadData]; make sure the array returned by [self loadData] is mutable too...other wise do this and try again NSMutableArray *loadedArray = [[self loadData]mutable copy]; — Shubhank
– Shubhank, Commented Mar 15, 2012 at 5:04
Try this NSMutableArray *loadedArray = [[NSMutableArray alloc] initWithArray:[self loadData]]; — user1025560
– user1025560, Commented Mar 15, 2012 at 5:19
hi, thanks for answering, mutableCopy is correct. It works fine now. — user1035877
– user1035877, Commented Mar 16, 2012 at 9:46

Eldar Markov · Accepted Answer · 2012-03-15 07:06:38Z

1

Your code looks clear. The only white spot is the way you create array in [self loadData] method.

You mentioned that you restore it from NSUserDefaults. Probably you just return it by [[NSUserDefaults standardUserDefaults] objectForKey:@"schools"].

Since objectForKey: method returns id type object you don't get a warning telling that objectForKey: returns NSArray not NSMutableArray.

Just make something like this:

return [NSMutableArray arrayWithArray:[[NSUserDefaults standardUserDefaults] objectForKey:@"schools"]];

I hope I guessed your code right ;)

answered Mar 15, 2012 at 7:06

Eldar Markov

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Comments

MadhavanRP · Accepted Answer · 2012-03-15 07:07:02Z

0

It would help if you put up the log, so we'll know what the crash actually is. I assume at some point you are storing values of tempArray into loaded. Try changing your code to this

 NSMutableDictionary *schools = [[NSMutableDictionary alloc] init];
    [schools setObject:name forKey:kFavoriteSchoolName];
    //load data is getting data from NSUserDefault which I save
    NSMutableArray *loadedArray = [[self loadData] retain];

//if loadedarray has object in there, then continue adding schools to it or make new array
if([loadedArray count] > 0)
{
    if([loadedArray isKindOfClass:[NSMutableArray class]]) {
    [loadedArray addObject:schools];
    }
    else {NSLog(@"Not a mutable array");}

    > // it crashes here


    [schools release];

    return [loadedArray autorelease];
} else
{ 
    [loadedArray release];
    //It will add the school to the array for the first time if there is nothing when it loaded.

    NSMutableArray *tempArray = [[[NSMutableArray alloc] init] autorelease];
    [tempArray addObject:schools];

    [schools release];

    return tempArray;
}

answered Mar 15, 2012 at 7:07

MadhavanRP

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1 Comment

user1035877 Over a year ago

Thanks for fast reply, I just edited my question. Please take a look again and help me out.

handiansom · Accepted Answer · 2017-03-28 16:38:24Z

0

I found out that you didn't initialize your array loadArray. You cannot add any value to uninitialized NSMutableArray.

You need to start with initialization.

NSMutableArray *loadArray  = [[NSMutableArray alloc]init];

Then populate data to your array

[loadArray  addObjectsFromArray:[self loadData]];

answered Mar 28, 2017 at 16:38

handiansom

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