example.swift

class MyOperation: Operation {
    open func execute() {

        let realm = try! Realm(configuration: Realm.Configuration(inMemoryIdentifier: "MyInMemoryRealm"))

        // Do some stuff
        
        networkClient.request(method: method, url: url, payload: payload) { statusCode, responseData, networkError in

            // Now do some stuff on original operation threafd
            
        }
    }
}