dynamic UITableView in static UITableViewCell

Question

Following setup causes trouble:

In my storyboard I have a standard table view controller, containing a table view with three static cells as content. One of the cells contains another table view with dynamic content and a prototype cell in it. Both table views' delegate and datasource are set to the same table view controller. In the delegate and datasource methods I determine which tableview has called the method and handle the response appropriately. However, if the dynamic table view contains more than one element I get a NSRangeException with [__NSArrayI objectAtIndex:]: index 1 beyond bounds [0 .. 0] . I was not able to track it down because the callstack has nothing in it which looks familiar to me. I suspected that my data was currupt but after polluting everthing with NSLog messages, it doesn't seem that way and I am still pretty lost.

Here is my code:

@interface CartViewController : UITableViewController

@property (nonatomic, strong) IBOutlet UITableView* cartTableView;
@property (nonatomic, strong) IBOutlet UILabel* lblTotalPrice;
@property (nonatomic, strong) IBOutlet UITableViewCell* cellProductList;
@property (nonatomic, strong) IBOutlet UITableViewCell* cellTotalPrice;
@property (nonatomic, strong) IBOutlet UITableViewCell* cellProceedToCheckout;

@end

@implementation CartViewController

@synthesize cartTableView;
@synthesize lblTotalPrice;
@synthesize cellProductList;
@synthesize cellTotalPrice;
@synthesize cellProceedToCheckout;

// other methods ...

#pragma mark - View lifecycle

- (void)viewDidLoad
{
    [super viewDidLoad];

    [[cartTableView layer] setCornerRadius:10];
    [cartTableView setTableFooterView:[[UIView alloc] initWithFrame:CGRectZero]];
    [cartTableView setClipsToBounds:YES];
}

- (void)viewWillAppear:(BOOL)animated
{
    [cartTableView reloadData];
    lblTotalPrice.text = [NSString stringWithFormat:@"%.2f €", [[DataStorage instance] shoppingCartTotalPrice]];
    [super viewWillAppear:animated];
}
#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    NSString* tableName = @"unknown";
    if(tableView == cartTableView)
        tableName = @"dynamic";
    if(tableView == self.tableView)
        tableName = @"static";

    int sections = 0;

    if (tableView == self.tableView)
        sections = 3;
    if (tableView == cartTableView)
        sections = 1;

    NSLog(@"%@ sections %d", tableName, sections);
    return sections;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    NSString* tableName = @"unknown";
    if(tableView == cartTableView)
        tableName = @"dynamic";
    if(tableView == self.tableView)
        tableName = @"static";

    int rows = 0;

    if (tableView == self.tableView && section < 3)
        rows = 1;
    if (tableView == cartTableView && section == 0)
        rows = [[DataStorage instance] shoppingCartItemCount];

    NSLog(@"%@ rows %d", tableName, rows);
    return rows;
}


- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    float height = 44;
    if (tableView == self.tableView)
    {
        if(indexPath.section == 0)
            height = UIInterfaceOrientationIsLandscape(self.interfaceOrientation)
            ? kCellProductListHeightLandscape
            : kCellProductListHeightPortrait;
    }
    else
    {
        height = kCartItemCellHeight;
    }

    return height;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell* cell = nil;

    NSString* tableName = @"unknown";
    if(tableView == cartTableView)
        tableName = @"dynamic";
    if(tableView == self.tableView)
        tableName = @"static";

    NSLog(@"%@ indexpath row %d section %d", tableName, indexPath.row, indexPath.section);

    if(tableView == cartTableView && indexPath.section == 0)
    {        
        ProductDefaultCell* cartItemCell = [tableView dequeueReusableCellWithIdentifier:kCellIdentifier];
        if (cartItemCell == nil) {
            cartItemCell = [[ProductDefaultCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:kCellIdentifier];
        }

        DataStorage* dataStorage = [DataStorage instance];

        ProductEntity* product = [dataStorage productFromCartAtIndex:indexPath.row];

        // set up cell data from product ...

        cell = cartItemCell;
    }
    else
    {
        switch (indexPath.section)
        {
            case 0:
                cell = cellProductList;
                break;
            case 1:
                cell = cellTotalPrice;
                break;
            case 2:
                cell = cellProceedToCheckout;
                break;
            default:
                break;
        }
    }

    NSLog(@"%@ %@", tableName, cell == nil ? @"error" : @"ok");

    return cell;
}

#pragma mark - Table view delegate

- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSString* tableName = @"unknown";
    if(tableView == cartTableView)
        tableName = @"dynamic";
    if(tableView == self.tableView)
        tableName = @"static";

    NSLog(@"%@ display row %d section %d", tableName, indexPath.row, indexPath.section);
}

Here is the console output:

2012-04-12 09:58:51.842 MyApp[363:fb03] dynamic sections 1
2012-04-12 09:58:51.856 MyApp[363:fb03] dynamic rows 2
2012-04-12 09:58:51.857 MyApp[363:fb03] dynamic sections 1
2012-04-12 09:58:51.857 MyApp[363:fb03] dynamic rows 2
2012-04-12 09:58:51.859 MyApp[363:fb03] static sections 3
2012-04-12 09:58:51.860 MyApp[363:fb03] static sections 3
2012-04-12 09:58:51.860 MyApp[363:fb03] static rows 1
2012-04-12 09:58:51.861 MyApp[363:fb03] static rows 1
2012-04-12 09:58:51.861 MyApp[363:fb03] static rows 1
2012-04-12 09:58:51.862 MyApp[363:fb03] static indexpath row 0 section 0
2012-04-12 09:58:51.862 MyApp[363:fb03] static ok
2012-04-12 09:58:51.863 MyApp[363:fb03] dynamic sections 1
2012-04-12 09:58:51.864 MyApp[363:fb03] dynamic rows 2
2012-04-12 09:58:51.864 MyApp[363:fb03] dynamic indexpath row 0 section 0
2012-04-12 09:58:51.978 MyApp[363:fb03] dynamic ok
2012-04-12 09:58:51.981 MyApp[363:fb03] dynamic display row 0 section 0
2012-04-12 09:58:51.991 MyApp[363:fb03] dynamic indexpath row 1 section 0
2012-04-12 09:58:52.053 MyApp[363:fb03] dynamic ok
objc[363]: EXCEPTIONS: throwing 0x6b6f670 (object 0x6b6fc20, a NSException)
objc[363]: EXCEPTIONS: searching through frame [ip=0x23d8678 sp=0xbfffc1a0] for exception 0x6b6f650
objc[363]: EXCEPTIONS: searching through frame [ip=0x23e2578 sp=0xbfffc1d0] for exception 0x6b6f650
objc[363]: EXCEPTIONS: searching through frame [ip=0x23e2673 sp=0xbfffd230] for exception 0x6b6f650
objc[363]: EXCEPTIONS: searching through frame [ip=0x23d8678 sp=0xbfffd4f0] for exception 0x6b6f650
objc[363]: EXCEPTIONS: searching through frame [ip=0x23e2578 sp=0xbfffd520] for exception 0x6b6f650
objc[363]: EXCEPTIONS: terminating
objc[363]: EXCEPTIONS: searching through frame [ip=0x1a0deed sp=0xbfffb6a0] for exception 0x6b6f650
objc[363]: EXCEPTIONS: catch(id)
objc[363]: EXCEPTIONS: unwinding through frame [ip=0x1a0deed sp=0xbfffb6a0] for exception 0x6b6f650
objc[363]: EXCEPTIONS: handling exception 0x6b6f650 at 0x1a0deff
2012-04-12 09:58:52.139 MyApp[363:fb03] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayI objectAtIndex:]: index 1 beyond bounds [0 .. 0]'
*** First throw call stack:
(0x187c022 0x1a0dcd6 0x1868644 0x8a7f88 0x6b41eb 0x51c008 0x51c3ce 0x507cbd 0x5166f1 0x4bfd42 0x187de42 0x23d8679 0x23e2579 0x23e2674 0x4b9967 0x670033 0x51be26 0x51c3ce 0x507cbd 0x5166f1 0x4bfd21 0x187de42 0x23d8679 0x23e2579 0x23674f7 0x23693f6 0x23f6160 0x491f30 0x185099e 0x17e7640 0x17b34c6 0x17b2d84 0x17b2c9b 0x1c7a7d8 0x1c7a88a 0x481626 0x247d 0x23e5)

Answer 1

I never figured out what was causing the problem, but instead I subclassed my TableViewCell (the one that contains the dynamic table) and let it implement the neccessary protocols and assigned the table views delegate and datasource to it, instead of the view controller of the static table view. That works perfectly fine and is probably better design anyway.

Here is some example code:

@interface CellWithTableInside : UITableViewCell <UITableViewDelegate, UITableViewDataSource>

@property (nonatomic, strong) UITableView* tableViewInCell;
@property (nonatomic, strong) NSArray* cellData;

@end

@implementation CellWithTableInside

@synthesize tableViewInCell;
@synthesize cellData = _cellData;

- (void)setCellData:(NSArray *)cellData
{
    _cellData = cellData;
    [tableViewInCell reloadData];
}

- (void)setFrame:(CGRect)frame
{
    [super setFrame:frame];
    [tableViewInCell setFrame:self.bounds];
}

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

- (id)initWithCoder:(NSCoder *)aDecoder
{
    self = [super initWithCoder:aDecoder];
    if (self) {
        [self setupTableView];
    }
    return self;
}

- (void)setupTableView
{
    tableViewInCell = [[UITableView alloc] initWithFrame:self.bounds];
    [tableViewInCell setDataSource:self];
    [tableViewInCell setDelegate:self];
    [self addSubview:tableViewInCell];
}

#pragma mark - Table view data source

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

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return self.cellData.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"NestedCell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
    }

    cell.textLabel.text = [self.cellData objectAtIndex:indexPath.row];
    return cell;
}

@end

You can use CellWithTableInside like this:

@interface HostingTableViewController : UITableViewController

@property (nonatomic, strong) NSArray* tableData;

@end

@implementation HostingTableViewController

@synthesize tableData;

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation
{
    return YES;
}

- (void)viewDidLoad
{
    tableData = [NSArray arrayWithObjects:
                 [NSArray arrayWithObjects:@"February", nil],
                 [NSArray arrayWithObjects:@"Apple", @"Banana", nil],
                 [NSArray arrayWithObjects:@"John", @"Peter", @"Edward", nil],
                 [NSArray arrayWithObjects:@"Yellow", @"Green", @"Red", @"Blue", nil],
                 nil];
}

#pragma mark - Table view data source

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

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return tableData.count;
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    return 44 * [(NSArray*)[tableData objectAtIndex:indexPath.row] count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"CellWithTableInside";
    CellWithTableInside *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[CellWithTableInside alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
    }

    [cell setCellData:[tableData objectAtIndex:indexPath.row]];
    return cell;
}

@end

This works for both, dynamic or static table views.