EXE Bad Access when Scrolling UITableView - iPhone

Question

I have a simple UITableView with 9 cells. When I move the table up or down by scrolling, I get EXE bad access. NSZombieMode points at the cellForRowAtIndexMethod.

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

UITableViewCell *cell =
[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
                                   reuseIdentifier:CellIdentifier];
}

cell.textLabel.text = [lineArray objectAtIndex:indexPath.row];
cell.accessoryType =  UITableViewCellAccessoryDisclosureIndicator;

return cell;
}

Can anyone suggest what is wrong ?

Answer 1

If ARC is disabled then add autorelease when you create cell

cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
                                   reuseIdentifier:CellIdentifier] autorelease];

This can be the reason of the leaks. Check also lineArray since it used like ivar and probably this array was released at some point.

Answer 2

My guess is you're trying to access an element in your lineArray that is out of bounds.

IE: indexPath.row is returning a 6 when you only have 3 elements in your lineArray.

It's occurring when you scroll down as it triggers cellForRowAtIndexPath to be called on higher number rows (rows that with indexPath.row > 3 for example)

I'll go one more step and guess that you're probably statically returning numberOfRowsForSection.

Setting it to lineArray.count should fix it.

Answer 3

According to my understanding :-

1) in the lineArray you have some 9 items but in the numberOfRowsInSection you are returning the rowCount more than the items in the array and so it crashes and points to ceelForRowAtIndex.

2) Here is the sample code for your understanding :-

- (void)viewDidLoad
{
    [super viewDidLoad];
    lineArray = [[NSMutableArray alloc]initWithObjects:@"1",@"2",@"3",@"4",@"5", nil];
    tableView1 = [[UITableView alloc]init];
    tableView1.delegate = self;
    tableView1.dataSource = self;
    tableView1 .frame =self.view.frame;
    [self.view addSubview:tableView1];

}

- (void)viewDidUnload
{
    [super viewDidUnload];
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
  return  [lineArray count];

    //return ;
}


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

    UITableViewCell *cell =
    [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
                                      reuseIdentifier:CellIdentifier];
    }

    cell.textLabel.text = [lineArray objectAtIndex:indexPath.row];
    cell.accessoryType =  UITableViewCellAccessoryDisclosureIndicator;

    return cell;
}


- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return 1;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{

}