firebase-ios-sdk/Firestore/Source/Public/FirebaseFirestore/FIRFirestoreSource.h

/*
 * Copyright 2018 Google
 *
 * 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.
 */

#import <Foundation/Foundation.h>

/**
 * An enum that configures the behavior of `DocumentReference.getDocument()` and
 * `Query.getDocuments()`.  By providing a source enum the `getDocument[s]`
 * methods can be configured to fetch results only from the server, only from
 * the local cache, or attempt to fetch results from the server and fall back to
 * the cache (which is the default).
 */
typedef NS_ENUM(NSUInteger, FIRFirestoreSource) {

  /**
   * Causes Firestore to try to retrieve an up-to-date (server-retrieved)
   * snapshot, but fall back to returning cached data if the server can't be
   * reached.
   */
  FIRFirestoreSourceDefault,

  /**
   * Causes Firestore to avoid the cache, generating an error if the server
   * cannot be reached. Note that the cache will still be updated if the
   * server request succeeds. Also note that latency-compensation still takes
   * effect, so any pending write operations will be visible in the returned
   * data (merged into the server-provided data).
   */
  FIRFirestoreSourceServer,

  /**
   * Causes Firestore to immediately return a value from the cache, ignoring
   * the server completely (implying that the returned value may be stale with
   * respect to the value on the server). If there is no data in the cache to
   * satisfy the `getDocument[s]` call, `DocumentReference.getDocument()` will
   * return an error and `QuerySnapshot.getDocuments()` will return an empty
   * `QuerySnapshot` with no documents.
   */
  FIRFirestoreSourceCache
} NS_SWIFT_NAME(FirestoreSource);