Question

My app is crashing when i scroll my TableView. First in my viewDidLoad method a load a dictionary from a file and for this dictionary i enumerate all keys.

 - (void)viewDidLoad {

     [super viewDidLoad];

     NSString *rootPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)objectAtIndex:0];      

     path = [rootPath stringByAppendingPathComponent:[NSString stringWithFormat:@"currency.archive"]]; 

     banks = [NSKeyedUnarchiver unarchiveObjectWithFile:path];

     keys = [banks allKeys];

     // set date for last update 
     dayMonthYear.text = [banks objectForKey:@"Last Updated"];
}

In my cellForRowAtIndexPath i populate cells with data from that dictionary. Anyway when my app starts everything looks fine, first five rows are drawn correctly, but when i start to scroll my app crash. My idea is that the problem is with autoreleased object here, i tried to retain them and after using them to release ,but unsuccessful. DEBUGGER SHOWS THAT MY PROBLEM IS AT LINE WITH BOLD

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

    NSString *CellIdentifier = [NSString stringWithFormat:@"Cell %d_%d",indexPath.section,indexPath.row];

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if (cell == nil) {      

        [[NSBundle mainBundle] loadNibNamed:@"CurrencyTableCell" owner:self options:nil];

        cell = currencyTableCell;

        //don't show selected cell
        cell.selectionStyle = UITableViewCellSelectionStyleNone;
        //set height
        self.cellHeight = cell.frame.size.height;
    }    

    // Fetch currency 
    NSString *currentCurrency = [keys objectAtIndex:indexPath.row];

    NSDictionary *fetchedCurrency = [banks objectForKey:currentCurrency];

    **NSString *name = [fetchedCurrency objectForKey:@"Currency Name"];**

    currencyTitle.text = name;

    NSString *charCode = [fetchedCurrency objectForKey:@"Code"];

    currencyCode.text = charCode;

    NSString* formattedNumber = [NSString stringWithFormat:@"%.02f",[[fetchedCurrency  objectForKey:@"Value"] floatValue]];

    if ([formattedNumber length] == 4) {
        formattedNumber = [NSString stringWithFormat:@"%@%@",@"0",formattedNumber];
    }

    buyPrice.text = formattedNumber;

    return cell;    
}

Answer 1

As a result from the discussion, [banks objectForKey:@"Last Updated"] gives you a NSString, not a NSDictionary!

You could get around this error by doing

if ([[banks objectForKey:currentCurrency] class] == [NSDictionary class]) { 
    ... rest of the code here .. 
}