firebase-ios-sdk/FirebaseCombineSwift/Sources/Auth/GameCenterAuthProvider+Combine.swift

// Copyright 2021 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#if canImport(Combine) && swift(>=5.0)

  import Combine
  import FirebaseAuth

  @available(swift 5.0)
  @available(iOS 13.0, macOS 10.15, macCatalyst 13.0, tvOS 13.0, *)
  @available(watchOS, unavailable)
  public extension GameCenterAuthProvider {
    /// Creates an `AuthCredential` for a Game Center sign in.
    ///
    /// The publisher will emit events on the **main** thread.
    ///
    /// - Returns: A publisher that emits an `AuthCredential` when the credential is obtained
    ///   successfully, or an error otherwise. The publisher will emit on the *main* thread.
    class func getCredential() -> Future<AuthCredential, Error> {
      Future<AuthCredential, Error> { promise in
        self.getCredential { authCredential, error in
          if let error = error {
            promise(.failure(error))
          } else if let authCredential = authCredential {
            promise(.success(authCredential))
          }
        }
      }
    }
  }

#endif // canImport(Combine) && swift(>=5.0)