透過 Apple 平台上的 Cloud Storage 上傳檔案

Cloud Storage for Firebase 可讓您快速輕鬆地將檔案上傳至 Firebase 提供並管理的 Cloud Storage 儲存體。

可建立參照

如要上傳檔案，請先建立 Cloud Storage 參照，指向您要上傳檔案的 Cloud Storage 位置。

您可以將子路徑附加至 Cloud Storage 儲存桶的根目錄，藉此建立參照：

Swift

// Create a root reference
let storageRef = storage.reference()

// Create a reference to "mountains.jpg"
let mountainsRef = storageRef.child("mountains.jpg")

// Create a reference to 'images/mountains.jpg'
let mountainImagesRef = storageRef.child("images/mountains.jpg")

// While the file names are the same, the references point to different files
mountainsRef.name == mountainImagesRef.name            // true
mountainsRef.fullPath == mountainImagesRef.fullPath    // false

Objective-C

// Create a root reference
FIRStorageReference *storageRef = [storage reference];

// Create a reference to "mountains.jpg"
FIRStorageReference *mountainsRef = [storageRef child:@"mountains.jpg"];

// Create a reference to 'images/mountains.jpg'
FIRStorageReference *mountainImagesRef = [storageRef child:@"images/mountains.jpg"];

// While the file names are the same, the references point to different files
[mountainsRef.name isEqualToString:mountainImagesRef.name];         // true
[mountainsRef.fullPath isEqualToString:mountainImagesRef.fullPath]; // false

您無法上傳參照 Cloud Storage 值區根目錄的資料。參照項目必須指向子網址。

上傳檔案

取得參照後，您可以透過兩種方式將檔案上傳至 Cloud Storage：

  1. 從記憶體中的資料上傳
  2. 從代表裝置上檔案的網址上傳

從記憶體中的資料上傳

putData:metadata:completion: 方法是將檔案上傳至 Cloud Storage 最簡單的方式。putData:metadata:completion: 會接收 NSData 物件並傳回 FIRStorageUploadTask，您可以使用 FIRStorageUploadTask 管理上傳內容並監控其狀態。

Swift

// Data in memory
let data = Data()

// Create a reference to the file you want to upload
let riversRef = storageRef.child("images/rivers.jpg")

// Upload the file to the path "images/rivers.jpg"
let uploadTask = riversRef.putData(data, metadata: nil) { (metadata, error) in
  guard let metadata = metadata else {
    // Uh-oh, an error occurred!
    return
  }
  // Metadata contains file metadata such as size, content-type.
  let size = metadata.size
  // You can also access to download URL after upload.
  riversRef.downloadURL { (url, error) in
    guard let downloadURL = url else {
      // Uh-oh, an error occurred!
      return
    }
  }
}

Objective-C

// Data in memory
NSData *data = [NSData dataWithContentsOfFile:@"rivers.jpg"];

// Create a reference to the file you want to upload
FIRStorageReference *riversRef = [storageRef child:@"images/rivers.jpg"];

// Upload the file to the path "images/rivers.jpg"
FIRStorageUploadTask *uploadTask = [riversRef putData:data
                                             metadata:nil
                                           completion:^(FIRStorageMetadata *metadata,
                                                        NSError *error) {
  if (error != nil) {
    // Uh-oh, an error occurred!
  } else {
    // Metadata contains file metadata such as size, content-type, and download URL.
    int size = metadata.size;
    // You can also access to download URL after upload.
    [riversRef downloadURLWithCompletion:^(NSURL * _Nullable URL, NSError * _Nullable error) {
      if (error != nil) {
        // Uh-oh, an error occurred!
      } else {
        NSURL *downloadURL = URL;
      }
    }];
  }
}];

從本機檔案上傳

您可以使用 putFile:metadata:completion: 方法，上傳裝置上的本機檔案，例如相機拍攝的相片和影片。putFile:metadata:completion: 會接收 NSURL 並傳回 FIRStorageUploadTask，您可以使用 FIRStorageUploadTask 管理上傳作業並監控其狀態。

Swift

// File located on disk
let localFile = URL(string: "path/to/image")!

// Create a reference to the file you want to upload
let riversRef = storageRef.child("images/rivers.jpg")

// Upload the file to the path "images/rivers.jpg"
let uploadTask = riversRef.putFile(from: localFile, metadata: nil) { metadata, error in
  guard let metadata = metadata else {
    // Uh-oh, an error occurred!
    return
  }
  // Metadata contains file metadata such as size, content-type.
  let size = metadata.size
  // You can also access to download URL after upload.
  riversRef.downloadURL { (url, error) in
    guard let downloadURL = url else {
      // Uh-oh, an error occurred!
      return
    }
  }
}

Objective-C

// File located on disk
NSURL *localFile = [NSURL URLWithString:@"path/to/image"];

// Create a reference to the file you want to upload
FIRStorageReference *riversRef = [storageRef child:@"images/rivers.jpg"];

// Upload the file to the path "images/rivers.jpg"
FIRStorageUploadTask *uploadTask = [riversRef putFile:localFile metadata:nil completion:^(FIRStorageMetadata *metadata, NSError *error) {
  if (error != nil) {
    // Uh-oh, an error occurred!
  } else {
    // Metadata contains file metadata such as size, content-type, and download URL.
    int size = metadata.size;
    // You can also access to download URL after upload.
    [riversRef downloadURLWithCompletion:^(NSURL * _Nullable URL, NSError * _Nullable error) {
      if (error != nil) {
        // Uh-oh, an error occurred!
      } else {
        NSURL *downloadURL = URL;
      }
    }];
  }
}];

如果您想主動管理上傳作業，可以使用 putData: 或 putFile: 方法並觀察上傳工作，而非使用完成處理常式。詳情請參閱「管理上傳內容」。

新增檔案中繼資料

您也可以在上傳檔案時加入中繼資料。這項中繼資料包含一般檔案中繼資料屬性，例如 name、size 和 contentType (通常稱為 MIME 類型)。putFile: 方法會自動從 NSURL 檔案名稱副檔名推斷內容類型，但您可以在中繼資料中指定 contentType，藉此覆寫自動偵測的類型。如果您沒有提供 contentType，且 Cloud Storage 無法從副檔名推斷預設值，Cloud Storage 會使用 application/octet-stream。如要進一步瞭解檔案中繼資料，請參閱「使用檔案中繼資料」一節。

Swift

// Create storage reference
let mountainsRef = storageRef.child("images/mountains.jpg")

// Create file metadata including the content type
let metadata = StorageMetadata()
metadata.contentType = "image/jpeg"

// Upload data and metadata
mountainsRef.putData(data, metadata: metadata)

// Upload file and metadata
mountainsRef.putFile(from: localFile, metadata: metadata)

Objective-C

// Create storage reference
FIRStorageReference *mountainsRef = [storageRef child:@"images/mountains.jpg"];

// Create file metadata including the content type
FIRStorageMetadata *metadata = [[FIRStorageMetadata alloc] init];
metadata.contentType = @"image/jpeg";

// Upload data and metadata
FIRStorageUploadTask *uploadTask = [mountainsRef putData:data metadata:metadata];

// Upload file and metadata
uploadTask = [mountainsRef putFile:localFile metadata:metadata];

管理上傳項目

除了開始上傳作業，您還可以使用 pause、resume 和 cancel 方法暫停、繼續及取消上傳作業。這些方法會觸發 pause、resume 和 cancel 事件。取消上傳會導致上傳失敗，並顯示上傳已取消的錯誤訊息。

Swift

// Start uploading a file
let uploadTask = storageRef.putFile(from: localFile)

// Pause the upload
uploadTask.pause()

// Resume the upload
uploadTask.resume()

// Cancel the upload
uploadTask.cancel()

Objective-C

// Start uploading a file
FIRStorageUploadTask *uploadTask = [storageRef putFile:localFile];

// Pause the upload
[uploadTask pause];

// Resume the upload
[uploadTask resume];

// Cancel the upload
[uploadTask cancel];

監控上傳進度

您可以將觀察器附加至 FIRStorageUploadTask，以監控上傳進度。新增觀察器會傳回 FIRStorageHandle，可用來移除觀察器。

Swift

// Add a progress observer to an upload task
let observer = uploadTask.observe(.progress) { snapshot in
  // A progress event occured
}

Objective-C

// Add a progress observer to an upload task
FIRStorageHandle observer = [uploadTask observeStatus:FIRStorageTaskStatusProgress
                                              handler:^(FIRStorageTaskSnapshot *snapshot) {
                                                // A progress event occurred
                                              }];

您可以將下列觀察器新增至 FIRStorageTaskStatus 事件：

FIRStorageTaskStatus 個事件 常見用途
FIRStorageTaskStatusResume 這個事件會在工作開始或繼續上傳時觸發，通常會與 FIRStorageTaskStatusPause 事件一併使用。
FIRStorageTaskStatusProgress 此事件會在資料上傳至 Cloud Storage 時觸發，可用於填入上傳進度指標。
FIRStorageTaskStatusPause 每次上傳暫停時，系統都會觸發這項事件，而且通常會與 FIRStorageTaskStatusResume 事件搭配使用。
FIRStorageTaskStatusSuccess 上傳完成後，系統會觸發這項事件。
FIRStorageTaskStatusFailure 上傳失敗時會觸發此事件。檢查錯誤，找出失敗原因。

事件發生時，系統會傳回 FIRStorageTaskSnapshot 物件。這個快照是事件發生時，對工作不可變動的檢視畫面。這個物件包含下列屬性：

屬性 類型 說明
progress NSProgress 包含上傳進度的 NSProgress 物件。
error NSError 上傳期間發生的錯誤 (如果有)。
metadata FIRStorageMetadata 上傳期間包含正在上傳的中繼資料。FIRTaskStatusSuccess 事件後，包含上傳檔案的中繼資料。
task FIRStorageUploadTask 這是快照的任務，可用於管理 (pause、resume、cancel) 任務。
reference FIRStorageReference 這項工作的參照來源。

您也可以依狀態個別移除觀察者，或是一次移除所有觀察者。

Swift

// Create a task listener handle
let observer = uploadTask.observe(.progress) { snapshot in
  // A progress event occurred
}

// Remove an individual observer
uploadTask.removeObserver(withHandle: observer)

// Remove all observers of a particular status
uploadTask.removeAllObservers(for: .progress)

// Remove all observers
uploadTask.removeAllObservers()

Objective-C

// Create a task listener handle
FIRStorageHandle observer = [uploadTask observeStatus:FIRStorageTaskStatusProgress
                                              handler:^(FIRStorageTaskSnapshot *snapshot) {
                                                // A progress event occurred
                                              }];

// Remove an individual observer
[uploadTask removeObserverWithHandle:observer];

// Remove all observers of a particular status
[uploadTask removeAllObserversForStatus:FIRStorageTaskStatusProgress];

// Remove all observers
[uploadTask removeAllObservers];

為避免記憶體流失，系統會在 FIRStorageTaskStatusSuccess 或 FIRStorageTaskStatusFailure 發生後移除所有觀察器。

處理錯誤

上傳時可能發生錯誤的原因有很多，包括本機檔案不存在，或是使用者沒有權限上傳所需檔案。如要進一步瞭解錯誤，請參閱說明文件的「處理錯誤」一節。

完整範例

以下是上傳內容的完整範例，其中包含進度監控和錯誤處理功能：

Swift

// Local file you want to upload
let localFile = URL(string: "path/to/image")!

// Create the file metadata
let metadata = StorageMetadata()
metadata.contentType = "image/jpeg"

// Upload file and metadata to the object 'images/mountains.jpg'
let uploadTask = storageRef.putFile(from: localFile, metadata: metadata)

// Listen for state changes, errors, and completion of the upload.
uploadTask.observe(.resume) { snapshot in
  // Upload resumed, also fires when the upload starts
}

uploadTask.observe(.pause) { snapshot in
  // Upload paused
}

uploadTask.observe(.progress) { snapshot in
  // Upload reported progress
  let percentComplete = 100.0 * Double(snapshot.progress!.completedUnitCount)
    / Double(snapshot.progress!.totalUnitCount)
}

uploadTask.observe(.success) { snapshot in
  // Upload completed successfully
}

uploadTask.observe(.failure) { snapshot in
  if let error = snapshot.error as? NSError {
    switch (StorageErrorCode(rawValue: error.code)!) {
    case .objectNotFound:
      // File doesn't exist
      break
    case .unauthorized:
      // User doesn't have permission to access file
      break
    case .cancelled:
      // User canceled the upload
      break

    /* ... */

    case .unknown:
      // Unknown error occurred, inspect the server response
      break
    default:
      // A separate error occurred. This is a good place to retry the upload.
      break
    }
  }
}

Objective-C

// Local file you want to upload
NSURL *localFile = [NSURL URLWithString:@"path/to/image"];

// Create the file metadata
FIRStorageMetadata *metadata = [[FIRStorageMetadata alloc] init];
metadata.contentType = @"image/jpeg";

// Upload file and metadata to the object 'images/mountains.jpg'
FIRStorageUploadTask *uploadTask = [storageRef putFile:localFile metadata:metadata];

// Listen for state changes, errors, and completion of the upload.
[uploadTask observeStatus:FIRStorageTaskStatusResume handler:^(FIRStorageTaskSnapshot *snapshot) {
  // Upload resumed, also fires when the upload starts
}];

[uploadTask observeStatus:FIRStorageTaskStatusPause handler:^(FIRStorageTaskSnapshot *snapshot) {
  // Upload paused
}];

[uploadTask observeStatus:FIRStorageTaskStatusProgress handler:^(FIRStorageTaskSnapshot *snapshot) {
  // Upload reported progress
  double percentComplete = 100.0 * (snapshot.progress.completedUnitCount) / (snapshot.progress.totalUnitCount);
}];

[uploadTask observeStatus:FIRStorageTaskStatusSuccess handler:^(FIRStorageTaskSnapshot *snapshot) {
  // Upload completed successfully
}];

// Errors only occur in the "Failure" case
[uploadTask observeStatus:FIRStorageTaskStatusFailure handler:^(FIRStorageTaskSnapshot *snapshot) {
  if (snapshot.error != nil) {
    switch (snapshot.error.code) {
      case FIRStorageErrorCodeObjectNotFound:
        // File doesn't exist
        break;

      case FIRStorageErrorCodeUnauthorized:
        // User doesn't have permission to access file
        break;

      case FIRStorageErrorCodeCancelled:
        // User canceled the upload
        break;

      /* ... */

      case FIRStorageErrorCodeUnknown:
        // Unknown error occurred, inspect the server response
        break;
    }
  }
}];

檔案上傳完成後，請參閱這篇文章，瞭解如何從 Cloud Storage下載檔案。