Common base class for ios view controllers using storyboards - ios

Question

I'm trying to use a base class MyBaseViewController that's a subclass of UIViewController for every view controller that I'll use in my app, so that I could have some things set up in that base controllers for convenience.
I created a storyboard with a UITableViewController object in it, and I'm writing a custom controller class MyTableViewController for it.
I wanted MyTableViewController to subclass MyBaseViewController and implement UITableViewDelegate and UITableViewDataSource for it to work properly with a table view, but when I tried to set the class for the UITableViewController object in my storyboard, it doesn't allow me to select the custom class I wrote.
I assume this is because the storyboard wants me to use a class that's a sub class of UITableViewController?
Is there a way to get this to work without changing MyTableViewController's inheritance?

Answer 1

Unfortunately not. Objective C doesn't support multiple inheritance.
I don't know what kind of defaults you're setting up in MyBaseViewController but if you moved them to an extension of UIViewController you could then have MyTableViewController and MyBaseViewController both call the same extension methods.

Answer 2

In a word, no. UITableViewController's ancestry is already defined. It inherits directly from UIViewController. You can't insert a new ancestor after the fact.
Objective-C doesn't have multiple inheritance, which would make this easy.
You could define your own subclass of UIViewController that implements the table view delegate and data source methods, and use that instead of a UITableViewController as the base class for your table view, but some things won't work unless the host of your table view is a UITableViewController.
If you don't need to add instance variables to your view controllers or override existing methods you might be able to define a category of UIController (UIViewController+MyMethods).
You might also create a set of methods that you add to both a custom subclass of UIViewController and UITableViewController. If you put your extra source code into a separate source file you could #include that source file in the body of your MyViewController.m. and your MyTableViewController.m files:
You might have a file ExtraVCMethods.m:
- (void) methodOne
{
//code
}
- (void) methodTwo
{
//code
}
And then in your MyViewController.m:
#implementation MyViewController
#include "ExtraVCMethods.m"
#end
And in your MyTableViewController.m:
#implementation MyTableViewController
#include "ExtraVCMethods.m"
#end
(Note that I am #including a .m file, not a .h file, and the #include goes inside the implementation, which is unusual.)
The #include would cause the compiler to insert the same source in the body of both classes. That way if you change the source for your extra methods you don't have to change it in 2 places.
Note that with the above approach you turn off the target membership checkbox for your ExtraVCMethods.m file. You don't want that compiled separately - just pasted into your other source files by the precompiler.