Question

I’m trying to make my own version of UITableViewController in a UIViewController (for more customization). So in my superclass, I’m implementing both the delegate and datasource and setting the UITableView object delegate and datasource properties to “this”. Only problem is I get a compiler warning complaining that I haven’t implemented the mandatory dataSource and delegate methods. I’d like to be able to implement these methods when I subclass my custom UITableViewController.

Is there a neat way to make these warnings go away, or is the only way for me to put empty versions of the mandatory delegate methods, and then override them in the subclass? Is this bad practice? Anyone have any insight on how Apple accomplishes this with there UITableViewController class?

Answer 1

I use this pattern for “abstract” methods:

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    [self doesNotRecognizeSelector:_cmd];
    abort();
}

The _cmd variable is the selector of the current method. It’s automatically provided, just like self.

You have to call abort() because the compiler knows that abort() doesn’t return, but it doesn’t know that about doesNotRecognizeSelector:.

At least in iOS 5, the UITableViewController methods aren’t empty, because UITableViewController supports loading predefined (static) rows from a storyboard.