Swift Generic Class implementing an Objective-C Protocol

Question

My intention is to create a generic class in Swift which conforms to an Objective-C protocol:

The class is:

class BaseViewFactoryImpl<T> : NSObject, BaseView {
  func getNativeInstance() -> AnyObject {
    return String("fsd")
  }
}

The protocol BaseView is:

@protocol BaseView < NSObject >

- (id)getNativeInstance;

@end

The compiler tells me:

Type 'BaseViewFactoryImpl<T>' does not conform to protocol 'BaseView'

If I delete <T> then there is no error.

What is wrong here? How can I get the correct generic class implementation?

Answer 1

If you create a new generic view model, when you try to create any subclass of the generic view model, you need to declare the subclass as a generic class as well. It's kind of annoy.

For a better way, you can use typealias to declare the instance's type instead of using generic:

protocol BaseView {
    typealias T
    func getNativeInstance() -> T!
}

class StringViewModel : BaseView {

    typealias T = String

    func getNativeInstance() -> String! {
        return T()
    }

}

Answer 2

//BaseViewFactory.swift

class BaseViewFactoryImpl<T> : NSObject, BaseView {
    func getNativeInstance() -> AnyObject {
        return String("fsd")
    }

//BaseViewProtocol.h

@protocol BaseView <NSObject>

- (id)getNativeInstance;

@end

//BridgingHeader.h

#import "BaseClassProtocol.h"

Your code should work. Have you created the bridging header to import the obj-C protocol file?