empty case validating case failed(message: String) } extension ValidationResult: CustomStringConvertible { var description: String { switch self { case let .ok(message): return message case .empty: return "ະೖྗͰ͢" case .validating: return "..." case let .failed(message): return message } } } 1 https:/ /github.com/ReactiveX/RxSwift/blob/900035d78b37e440b9098d0ffac28e0d8b8cc660/RxExample/RxExample/Examples/GitHubSignup/ BindingExtensions.swift