ios - Generic controller in swift 2.0 using storyboards

Question

Im trying to create a GenericListController for my app.

I have a ProductListController that extend this generic controller which extends UIViewController. I have connected ProductListController to a storyboard and made 2 outlets, but i always receive this error:

 Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<UIViewController 0x7c158ca0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key searchBar.'

I receive this error for all my outlets, if i remove the generic T from GenericListController it works. I guess a storyboard cant load a super with generics. How can i make it work?

My code:

class GenericListController<T> : UIViewController {

    var list : [T] = [T]()
    var filteredlist : [T] = [T]()

    func getData(tableView : UITableView) {
    .....
    }

    func setData(list : [T], tableView : UITableView) {
    .....
    }

    override func viewDidLoad() {
       super.viewDidLoad()
      }
} 

class ProductListController : GenericListController<ProductModel> {
       @IBOutlet weak var searchBar: UISearchBar!
       @IBOutlet weak var tableView: UITableView!

     override func viewDidLoad() {
       super.viewDidLoad()

       getData(tableView)
     }
}

--EDIT--

I have found that if i extend an generic class and try to add the class to an storyboard xcode wont autocomplete the class name (probably because it cant detect the class)

Answer 1

This answers why it is not possible : use a generic class as a custom view in interface builder

Interface Builder "talks" to your code through the ObjC runtime. As such, IB can can access only features of your code that are representable in the ObjC runtime. ObjC doesn't do generics

This hint at a possible work around : generics in obj-c Maybe you can create a generic ViewController in obj-c and then IB will accept it?

Have you considered using a protocol? This doesn't upset the storyboard. Changed the code a bit to make it easily testable. The downside of this is that you can't have stored properties in a protocol. So you would still need to copy paste those. Upside is that it works.

protocol GenericListProtocol {       
    typealias T
    var list : [T] { get set }
    var filteredlist : [T] { get set }
    func setData(list : [T])        
}    
extension GenericListProtocol {        
    func setData(list: [T]) {
        list.forEach { item in print(item) }
    }        
}

class ProductModel {        
    var productID : Int = 0        
    init(id:Int) {
        productID = id
    }        
}    

class ProductListController: UIViewController, GenericListProtocol {

    var list : [ProductModel] = [ProductModel(id: 1),ProductModel(id: 2),ProductModel(id: 3),ProductModel(id: 4)]
    var filteredlist : [ProductModel] = []

    override func viewDidLoad() {            
        super.viewDidLoad()            
        setData(list)            
    }
}

---

Update: Allow some access to attributes to the generic class. Changed it to a basic class to easily test in a Playground. UIViewController stuff is in the code above.

class ProductModel {        
    var productID : Int = 0        
    init(id:Int) {
        productID = id
    }        
}

class ProductA : ProductModel {
    var aSpecificStuff : Float = 0
}    

class ProductB : ProductModel {
    var bSpecificStuff : String = ""
}

protocol GenericListProtocol {        
    typealias T = ProductModel
    var list : [T] { get set }
    var filteredlist : [T] { get set }
    func setData(list : [T])        
}

extension GenericListProtocol {        
    func setData(list: [T]) {
        list.forEach { item in
            guard let productItem = item as? ProductModel else {
                return
            }
            print(productItem.productID)
        }
    }        
}


class ProductListController: GenericListProtocol {

    var list : [ProductA] = [ProductA(id: 1),ProductA(id: 2),ProductA(id: 3),ProductA(id: 4)]
    var filteredlist : [ProductA] = []

    init() {            
        setData(list)            
    }
}

var test = ProductListController()