Question

EDIT: Ok, so i figured out how to remedy my original problem, but i’m not sure if this is the best way.

My new question is, say I have a subclass of UITableViewCell with the following property declaration in the header:

@property (nonatomic, retain) IBOutlet UILabel *levelLabel;

This is connected in IB. Is it ok to not release this in dealloc, and not release it at all? This is the only way I can figure out to get it to work, without giving me an exc_bad_access error. Before, it called dealloc when the tableviewcell went off the screen but then it still needed it. where do i release stuff, or does it take care of that for me?

Original Title: Memory leak in UITableView and exc_bad_access
Ok, I am confused. I was following along with this tutorial online making custom UITableViewCells. I made one, and i did everything like the tutorial told me. My UITableViewCell subclass contains 3 UILabels and 3 UIButtons, and has all of them defined as properties and connected in IB. I need them to be available to the class because i need to know when the buttons are pressed and be able to change the text. When I run the app, i start scrolling and after a few seconds it crashes, with exc_bad_access in main (no output in the console). But when I run the app in instruments with NSZombieEnabled, it does not crash at all, and runs just fine. However, since instruments shows you the allocations, i can see them going up very quickly, especially as I scroll. I dont know if this is all allocations, or if these are being released, but still it seems too fast.

Here is PointCoordinatesCell.h (my custom cell):

#import <UIKit/UIKit.h>

@interface PointCoordinatesCell : UITableViewCell


@property (nonatomic, retain) IBOutlet UILabel *levelLabelLabel;
@property (nonatomic, retain) IBOutlet UILabel *levelLabel;
@property (nonatomic, retain) IBOutlet UILabel *levelDescriptionLabel;
@property (nonatomic, retain) IBOutlet UIButton *beginningButton;
@property (nonatomic, retain) IBOutlet UIButton *developingButton;
@property (nonatomic, retain) IBOutlet UIButton *secureButton;

@end

PointCoordinatesCell.m:

#import "PointCoordinatesCell.h"

@implementation PointCoordinatesCell
@synthesize levelLabel, levelLabelLabel, levelDescriptionLabel, beginningButton, developingButton, secureButton;

- (void)dealloc{
    [super dealloc];
    [levelLabel release];
    [levelLabelLabel release];
    [levelDescriptionLabel release];
    [beginningButton release];
    [developingButton release];
    [secureButton release];
}

- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier
{
    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
    if (self) {
        // Initialization code
    }
    return self;
}

- (void)setSelected:(BOOL)selected animated:(BOOL)animated
{
    [super setSelected:selected animated:animated];

    // Configure the view for the selected state
}

@end

RootViewController.h has nothing in it other than a class declaration and standard imports. No variables or methods defined. It subclasses UITableViewController.

RootViewController.m:

#import "RootViewController.h"
#import "StatesAppDelegate.h"
#import "PointCoordinatesCell.h"

@implementation RootViewController

- (void)viewDidLoad {
    [super viewDidLoad];


    // Uncomment the following line to display an Edit button in the navigation bar for this view controller.
    // self.navigationItem.rightBarButtonItem = self.editButtonItem;
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning]; // Releases the view if it doesn't have a superview
    // Release anything that's not essential, such as cached data
}

#pragma mark Table view methods

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return 1;
}


// Customize the number of rows in the table view.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return 50;
}


- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath;
{
    return 293;
}

// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    static NSString *CellIdentifier = @"PointCoordinatesCell";

    PointCoordinatesCell *cell = (PointCoordinatesCell *) [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {

        NSArray *topLevelObjects = [[NSBundle mainBundle] loadNibNamed:@"PointCoordinatesCell" owner:self options:nil];

        for (id currentObject in topLevelObjects){
            if ([currentObject isKindOfClass:[UITableViewCell class]]){
                cell =  (PointCoordinatesCell *) currentObject;
                break;
            }
        }
    }

    //cell.capitalLabel.text = [capitals objectAtIndex:indexPath.row];
    //cell.stateLabel.text = [states objectAtIndex:indexPath.row];

    return cell;
}


- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    // Navigation logic may go here. Create and push another view controller.
    // AnotherViewController *anotherViewController = [[AnotherViewController alloc] initWithNibName:@"AnotherView" bundle:nil];
    // [self.navigationController pushViewController:anotherViewController];
    // [anotherViewController release];
}



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


@end

Answer 1

It seems you are doing some complicated casting in your cellForRowAtIndexPath method. I do not think this is necessary. It does not seem logical to me to check for an object of class UITableViewCell and then cast it into a custom cell. The cell in your nib should already be a custom cell.

In the Apple sample the loading of the cell is much more straight forward. You link your custom cell to an IBOutlet in your view controller and then do this:

CustomCell *cell = (CustomCell *) [aTableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
    [[NSBundle mainBundle] loadNibNamed:@"CustomCell" owner:self options:nil];
    cell = customTableViewCell;
    self.customTableViewCell = nil;
    // etc.
}