typealias CompletionResponse = ((_ response: AnyObject) -> Void)?

class SomeClass {

    static let shared = SomeClass()

    var completion: CompletionResponse?

    func getSomthing(completion: CompletionResponse) {
        self.completion = completion
    }

    func someDelegateMethode(info: [String]) {
        // Error is here
        if let completion = self.completion {
            completion(info)
        }
    }
}

 let x = SomeClass()

x.getSomthing { (obj) in
    print(obj as! [String])
}

x.someDelegateMethode(info: ["Hello", "There"])