UITableView application crushes when scrolling way too down

Question

Hi,

When I am scrolling my table way too down, application crushes. And I cannot find where the error in code is.

Here is my code:

NSMutableDictionary *tableDataDictionary;
NSInteger *rows_in_section;


-(void) initView
{
    if (!tableDataDictionary)
    {
     tableDataDictionary = [ [NSMutableDictionary alloc] init];
    }
    [self reloadTableData];
}

-(void)viewDidDisappear:(BOOL)animated {
    [super viewDidDisappear:animated];
    [mainTableView deselectRowAtIndexPath: [mainTableView indexPathForSelectedRow] animated:NO];

    [tableDataDictionary release];
    tableDataDictionary = nil;
    free(rows_in_section);
}

-(void) reloadTableData {
    [tableDataDictionary removeAllObjects];


    //Sections
    if (rows_in_section)
    {
     free(rows_in_section);
    }

    rows_in_section = (NSInteger*)calloc(25, sizeof(NSInteger));
    for (int i = 0; i <= 25; i++)
    {
     rows_in_section[i] = 0;
    }

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

    int cur_section = -1;

    while ( TRUE )
    {
     WordObject *tempWordObj = [ [WordsDatabase sharedWordsDatabase] getNextWordABC];
     if (!tempWordObj)
     {
      [tableDataDictionary setObject:words_in_section forKey:[NSNumber numberWithInt: cur_section] ];
      [tempWordObj release];

      [tableDataDictionary setObject:[words_in_section copy] forKey:[NSNumber numberWithInt: cur_section] ];
      [words_in_section removeAllObjects];

      break;
     }

     //First loop
     if (cur_section == -1) cur_section = toupper([ [tempWordObj word] characterAtIndex:0 ] ) - 'A';

     //If a has letter changed, assign the previous array to a dictionary
     if ( (toupper([ [tempWordObj word] characterAtIndex:0 ] ) - 'A') != cur_section )
     {
      [tableDataDictionary setObject:[words_in_section copy] forKey:[NSNumber numberWithInt: cur_section] ];
      [words_in_section removeAllObjects];
     }

     cur_section = toupper([ [tempWordObj word] characterAtIndex:0 ] ) - 'A';

     [words_in_section addObject:tempWordObj];

     [tempWordObj release];
     tempWordObj = nil;

     rows_in_section[cur_section]++;

    }

    [words_in_section release];

    [ [WordsDatabase sharedWordsDatabase] endGettingWordsABC];


    [mainTableView reloadData];
    [mainTableView scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0] atScrollPosition:UITableViewScrollPositionBottom animated:NO];

}


//
// Table handling
//

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return 26;
}

// Customize the number of rows in the table view.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return rows_in_section[section];
}

// Adding a section index here 
- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView 
{ 
    return ALPHA_ARRAY; 
} 

- (NSInteger)tableView:(UITableView *)tableView sectionForSectionIndexTitle:(NSString *)title atIndex:(NSInteger)index {
    return index;
}


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    DebugLog(@"cellForRowAtIndexPath");
    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier] autorelease];
    }


    WordObject *tempWordObj = [ [tableDataDictionary objectForKey: [NSNumber numberWithInt:[indexPath section] ] ] objectAtIndex: [indexPath row] ];

    if (!tempWordObj)
    {
     DebugLog(@"!tempWordObj");
     return cell;
    }

    cell.text = [tempWordObj word];

    [tempWordObj release];

    return cell;
}

How can I solve this problem with scrolling down and why it occurs? And if you will find any other disadvantages in my code, please tell me this.

Thank you in advance, Ilya.

Answer 1

You do not need this line;

[tempWordObj release];

[NSDictionary objectForKey] returns an auto-released object, that is the object will be automatically released sometime after your function returns.