how to connect to IBOutlet or IBAction in base class

Question

I have a base view controller class which inherits from UIViewController and an inherited class from the base viewcontroller class. Now I have a nib whose file owner is the inherited class but all my actions and outlets are in the base class. Is it even possible to connect the action\outlet in the nib file to that in the base class?

Answer 1

I'll be basically explain it by example:

Define a base class (let's call it BaseViewController) and assign it a UITableView IBoutlet in the .h file:

//  BaseViewController.h
@interface BaseViewController : UIViewController    
@property (weak, nonatomic) IBOutlet UITableView *tableView;    
@end

Define two children classes (ie FirstChildViewController and SecondChildViewController):

// FirstChildViewController.h
@interface FirstChildViewController : BaseViewController
@end

// SecondChildViewController.h
@interface SecondChildViewController : BaseViewController
@end

Now to make either (or both of) the children classes use the iboutlet of the base class, simply drag the referencing outlet to the property definition in the base class .h file.. and that's it!

here is a complete project that illustrates this.

Answer 2

Two ways to accomplish this:

1)

do it programmatically (i.e. in code)

First declare your outlets in the base class.

and then assign your outlets via code in your inherited class.

and

2)

You can also assign your outlets and actions in your XIB file. Xcode knows about inherited outlets and actions from base classes.

Answer 3

If the base class is in a Swift framework, then sometimes Xcode 7 will not see the outlets, even if the base class and its outlets are public. In this case the workaround is as follows:

1. In IB set the control to use the base class
2. Connect the outlets
3. In IB set the control to use the derived class

IB will show "!" next to the outlets as if they are missing, but there will be no errors at runtime.

If someone has a better workaround, let me know!