How to acess swift 5 Result enum type in objective-c

Question

I have written a class method in swift-5 with it's parameter Result type, now I want to use this method in objective-c, is it possible? if yes, how?

@objc public class DemoClass :NSObject {

    @objc public func demoMethod(completion: @escaping (Result<UIImage,Error>) -> 
     Void) {
             //some codes
      }
}

As soon as I add @objc to method it throws an error: Method cannot be marked @objc because the type of the parameter cannot be represented in Objective-C

Answer 1

The enum Result is inaccessible in Objective-C. It is @frozen and not @inlinable .

And also Objective-C enums cannot be generic, ie, the Result<Success, Failure> where Failure: Error cannot to exposed to Objective-C.

So, what can you do is make a class as follows and do other stuffs as required:

@objc class AResult: NSObject {
    
    public private(set) var success: Any?
    public private(set) var failure: Error?
    
    private override init() {
        super.init()
        success = nil
        failure = nil
    }
    
    public convenience init<Success, Failure>(_ arg1: Success, _ arg2: Failure) where Failure: Error {
        self.init()
        success = arg1
        failure = arg2
        // Do something
    }
}

And declare your function: @objc func demoMethod(_ completion: (AResult) -> Void) {}

Hope this helps.