Add API docs for FirebaseStorageSwift (#5241)

FirebaseStorageSwift/Sources/SwiftAPIExtension.swift

@@ -14,8 +14,14 @@
 
 import FirebaseStorage
 
-/// getResultCallback generates a closure that returns a Result type from a closure that returns an
-/// optional type and Error.
+/// Generates a closure that returns a `Result` type from a closure that returns an optional type
+/// and `Error`.
+///
+/// - Parameters:
+///   - completion: A completion block returning a `Result` enum with either a generic object or
+///                 an `Error`.
+/// - Returns: A closure parameterized with an optional generic and optional `Error` to match
+///            Objective C APIs.
 private func getResultCallback<T>(
   completion: @escaping (Result<T, Error>) -> Void
 ) -> (_: T?, _: Error?) -> Void {
@@ -35,19 +41,56 @@ private func getResultCallback<T>(
 }
 
 public extension StorageReference {
+  /// Asynchronously retrieves a long lived download URL with a revokable token.
+  /// This can be used to share the file with others, but can be revoked by a developer
+  /// in the Firebase Console if desired.
+  ///
+  /// - Parameters:
+  ///   - completion: A completion block returning a `Result` enum with either a URL or an `Error`.
   func downloadURL(completion: @escaping (Result<URL, Error>) -> Void) {
     downloadURL(completion: getResultCallback(completion: completion))
   }
 
+  /// Asynchronously downloads the object at the `StorageReference` to a `Data` object.
+  /// A `Data` of the provided max size will be allocated, so ensure that the device has enough
+  /// memory to complete. For downloading large files, writeToFile may be a better option.
+
+  /// - Parameters:
+  ///   - maxSize: The maximum size in bytes to download.
+  ///   - completion: A completion block returning a `Result` enum with either a `Data` object or
+  ///                 an `Error`.
+  ///
+  /// - Returns: A StorageDownloadTask that can be used to monitor or manage the download.
   func getData(maxSize: Int64, completion: @escaping (Result<Data, Error>) -> Void)
     -> StorageDownloadTask {
     return getData(maxSize: maxSize, completion: getResultCallback(completion: completion))
   }
 
+  /// Retrieves metadata associated with an object at the current path.
+  ///
+  /// - Parameters:
+  ///   - completion: A completion block which returns a `Result` enum with either the
+  ///                 object metadata or an `Error`.
   func getMetadata(completion: @escaping (Result<StorageMetadata, Error>) -> Void) {
     getMetadata(completion: getResultCallback(completion: completion))
   }
 
+  /// Resumes a previous `list` call, starting after a pagination token.
+  /// Returns the next set of items (files) and prefixes (folders) under this StorageReference.
+  ///
+  /// "/" is treated as a path delimiter. Firebase Storage does not support unsupported object
+  /// paths that end with "/" or contain two consecutive "/"s. All invalid objects in GCS will be
+  /// filtered.
+  ///
+  /// Only available for projects using Firebase Rules Version 2.
+  ///
+  /// - Parameters:
+  ///   - withMaxResults The maximum number of results to return in a single page. Must be
+  ///                    greater than 0 and at most 1000.
+  ///   - pageToken A page token from a previous call to list.
+  ///   - completion A completion handler that will be invoked with the next items and
+  ///                prefixes under the current StorageReference. It returns a `Result` enum
+  ///                with either the list or an `Error`.
   func list(withMaxResults maxResults: Int64,
             pageToken: String,
             completion: @escaping (Result<StorageListResult, Error>) -> Void) {
@@ -56,16 +99,54 @@ public extension StorageReference {
          completion: getResultCallback(completion: completion))
   }
 
+  /// List up to `maxResults` items (files) and prefixes (folders) under this StorageReference.
+  ///
+  /// "/" is treated as a path delimiter. Firebase Storage does not support unsupported object
+  /// paths that end with "/" or contain two consecutive "/"s. All invalid objects in GCS will be
+  /// filtered.
+  ///
+  /// Only available for projects using Firebase Rules Version 2.
+  ///
+  /// - Parameters:
+  ///   - withMaxResults The maximum number of results to return in a single page. Must be
+  ///                    greater than 0 and at most 1000.
+  ///   - completion A completion handler that will be invoked with the next items and
+  ///                prefixes under the current `StorageReference`. It returns a `Result` enum
+  ///                with either the list or an `Error`.
   func list(withMaxResults maxResults: Int64,
             completion: @escaping (Result<StorageListResult, Error>) -> Void) {
     list(withMaxResults: maxResults,
          completion: getResultCallback(completion: completion))
   }
 
+  /// List all items (files) and prefixes (folders) under this StorageReference.
+  ///
+  /// This is a helper method for calling list() repeatedly until there are no more results.
+  /// Consistency of the result is not guaranteed if objects are inserted or removed while this
+  /// operation is executing. All results are buffered in memory.
+  ///
+  /// Only available for projects using Firebase Rules Version 2.
+  ///
+  /// - Parameters:
+  ///   - completion A completion handler that will be invoked with all items and prefixes
+  ///                under the current StorageReference. It returns a `Result` enum with either the
+  ///                list or an `Error`.
   func listAll(completion: @escaping (Result<StorageListResult, Error>) -> Void) {
     listAll(completion: getResultCallback(completion: completion))
   }
 
+  /// Asynchronously uploads data to the currently specified `StorageReference`.
+  /// This is not recommended for large files, and one should instead upload a file from disk.
+  ///
+  /// - Parameters:
+  ///   - uploadData The `Data` to upload.
+  ///   - metadata `StorageMetadata` containing additional information (MIME type, etc.)
+  ///              about the object being uploaded.
+  ///   - completion A completion block that returns a `Result` enum with either the
+  ///                object metadata or an `Error`.
+  ///
+  /// - Returns: An instance of `StorageUploadTask`, which can be used to monitor or manage
+  ///            the upload.
   func putData(_ uploadData: Data,
                metadata: StorageMetadata? = nil,
                completion: @escaping (Result<StorageMetadata, Error>) -> Void)
@@ -75,6 +156,17 @@ public extension StorageReference {
                    completion: getResultCallback(completion: completion))
   }
 
+  /// Asynchronously uploads a file to the currently specified `StorageReference`.
+  ///
+  /// - Parameters:
+  ///   - from A URL representing the system file path of the object to be uploaded.
+  ///   - metadata `StorageMetadata` containing additional information (MIME type, etc.)
+  ///              about the object being uploaded.
+  ///   - completion A completion block that returns a `Result` enum with either the
+  ///                object metadata or an `Error`.
+  ///
+  /// - Returns: An instance of `StorageUploadTask`, which can be used to monitor or manage
+  ///            the upload.
   func putFile(from: URL,
                metadata: StorageMetadata? = nil,
                completion: @escaping (Result<StorageMetadata, Error>) -> Void)
@@ -84,11 +176,26 @@ public extension StorageReference {
                    completion: getResultCallback(completion: completion))
   }
 
+  /// Updates the metadata associated with an object at the current path.
+  ///
+  /// - Parameters:
+  ///   - metadata A `StorageMetadata` object with the metadata to update.
+  ///   - completion A completion block which returns a `Result` enum with either the
+  ///                object metadata or an `Error`.
   func updateMetadata(_ metadata: StorageMetadata,
                       completion: @escaping (Result<StorageMetadata, Error>) -> Void) {
     return updateMetadata(metadata, completion: getResultCallback(completion: completion))
   }
 
+  /// Asynchronously downloads the object at the current path to a specified system filepath.
+  ///
+  /// - Parameters:
+  ///   - toFile A file system URL representing the path the object should be downloaded to.
+  ///   - completion A completion block that fires when the file download completes. The
+  ///                block returns a `Result` enum with either an NSURL pointing to the file
+  ///                path of the downloaded file or an `Error`.
+  ///
+  /// - Returns: A `StorageDownloadTask` that can be used to monitor or manage the download.
   func write(toFile: URL, completion: @escaping (Result<URL, Error>)
     -> Void) -> StorageDownloadTask {
     return write(toFile: toFile, completion: getResultCallback(completion: completion))