Question

So I’ve been trying to load cells from a UITableView and put those into an NSMutableArray to be iterated through later. I have a method called populateArrayWithCells which works fine until I put in more than 6 cells. For some reason the object returned is nil. My code is below, StocksAndAccounts is the UITableView and I have subclassed the UITableViewCells in section 1.

- (void) populateArrayWithCells
{
for (int i = 0; i < [StocksAndAccounts numberOfRowsInSection:1]; i++) {
    if ([StocksAndAccounts cellForRowAtIndexPath:[NSIndexPath indexPathForRow:i inSection:1]] == nil) {
        NSLog(@"object at index %i is nil", i);
    }
    [stocksCells addObject:[StocksAndAccounts cellForRowAtIndexPath:[NSIndexPath indexPathForRow:i inSection:1]]];
}
}

This function, when called through an IBAction, returns the cell successfuly until the index is 6, in which case it is nil and crashes because it’s trying to add an object that is nil. Any help with this problem would be greatly appreciated.

Answer 1

I think you’ve misunderstood how UITableViews work. The cells in a tableview are only loaded when they need to be displayed, and they are recycled, so if you can only see six cells on screen at a time then the table will only ever contain six cells and it will just keep updating and reusing those same six as you scroll up and down.

Instead of storing data in your table cells, store it in an array of custom objects in your view controller and use those objects to populate the cells when the table requests them from your datasource methods.

That way if you ever need to use that data for something other than displaying in the table, you can re-create it from the original object instead of trying to copy it out of the table cell.