为什么Interface Builder在身份检查器中不显示视图控制器子类？

Question

I have a BaseViewController and I want to inherit from this in a subclass. When I do this the subclass "TestViewController" doesn't appear under the class dropdown in Xcode's interface builder (see below image). Isn't this possible?

class BaseViewController<T: AnyObject> : UIViewController{

    var  test: T?

    override func viewDidLoad() { }

}

class TestViewController : BaseViewController<UIView>{ }

If I just type in the class name then I get a runtime error saying:

Unknown class TestViewController in Interface Builder file

Tried

• Removing references to files and adding them again
• Editing the storyboard using a text editor and adding name to attribute "customClass"

Answer 1

Pretty simple: You can't use a generic type here. The reason is that UIKit is written in ObjC, and generic types are not fully visible to ObjC. This answer goes into the details.