您的檔案儲存在 Cloud Storage 值區。 如同 本機硬碟上的檔案系統,或是 Firebase Realtime Database 中的資料。 建立檔案的參照後,應用程式就能取得該檔案的存取權。這些參考資料 可用來上傳/下載資料、取得或更新中繼資料,或是刪除 檔案。參照可以指向特定檔案或更高層級 資源階層
如果您已使用 Firebase Realtime Database,則這些路徑應該 不過,檔案資料會儲存在 Cloud Storage,不在 Realtime Database 中。
可建立參照
建立參考檔案來上傳、下載或刪除檔案 或是取得或更新中繼資料參考資料 可視為指向雲端檔案的指標參考檔案為 (數量不限),您可以視需要建立各種檔案。如有需要,也能重複使用 多項作業
參照是使用 FirebaseStorage
服務建立,並呼叫其
reference
方法。
Swift
// Get a reference to the storage service using the default Firebase App let storage = Storage.storage() // Create a storage reference from our storage service let storageRef = storage.reference()
Objective-C
// Get a reference to the storage service using the default Firebase App FIRStorage *storage = [FIRStorage storage]; // Create a storage reference from our storage service FIRStorageReference *storageRef = [storage reference];
您可以建立對樹狀圖中下方位置的參照
呼叫 'images/space.jpg'
,方法是對現有參照使用 child
方法。
Swift
// Create a child reference // imagesRef now points to "images" let imagesRef = storageRef.child("images") // Child references can also take paths delimited by '/' // spaceRef now points to "images/space.jpg" // imagesRef still points to "images" var spaceRef = storageRef.child("images/space.jpg") // This is equivalent to creating the full reference let storagePath = "\(your_firebase_storage_bucket)/images/space.jpg" spaceRef = storage.reference(forURL: storagePath)
Objective-C
// Create a child reference // imagesRef now points to "images" FIRStorageReference *imagesRef = [storageRef child:@"images"]; // Child references can also take paths delimited by '/' // spaceRef now points to "images/space.jpg" // imagesRef still points to "images" FIRStorageReference *spaceRef = [storageRef child:@"images/space.jpg"]; // This is equivalent to creating the full reference spaceRef = [storage referenceForURL:@"gs://<your-firebase-storage-bucket>/images/space.jpg"];
使用參考資料進行導覽
您也可以使用 parent
和 root
方法在
檔案階層parent
會向上導覽一個層級
root
則會一直導覽到頂端。
Swift
// Parent allows us to move to the parent of a reference // imagesRef now points to 'images' let imagesRef = spaceRef.parent() // Root allows us to move all the way back to the top of our bucket // rootRef now points to the root let rootRef = spaceRef.root()
Objective-C
// Parent allows us to move to the parent of a reference // imagesRef now points to 'images' imagesRef = [spaceRef parent]; // Root allows us to move all the way back to the top of our bucket // rootRef now points to the root FIRStorageReference *rootRef = [spaceRef root];
child
、parent
和 root
可以多次鏈結,例如
每個物件都會傳回一個參照例外狀況是 root
的 parent
,
為 nil
。
Swift
// References can be chained together multiple times // earthRef points to "images/earth.jpg" let earthRef = spaceRef.parent()?.child("earth.jpg") // nilRef is nil, since the parent of root is nil let nilRef = spaceRef.root().parent()
Objective-C
// References can be chained together multiple times // earthRef points to "images/earth.jpg" FIRStorageReference *earthRef = [[spaceRef parent] child:@"earth.jpg"]; // nilRef is nil, since the parent of root is nil FIRStorageReference *nilRef = [[spaceRef root] parent];
參照屬性
你可以檢查參照,進一步瞭解指標指向的檔案
方法是使用 fullPath
、name
和 bucket
屬性。這些屬性
取得檔案的完整路徑、名稱和值區。
Swift
// Reference's path is: "images/space.jpg" // This is analogous to a file path on disk spaceRef.fullPath // Reference's name is the last segment of the full path: "space.jpg" // This is analogous to the file name spaceRef.name // Reference's bucket is the name of the storage bucket where files are stored spaceRef.bucket
Objective-C
// Reference's path is: "images/space.jpg" // This is analogous to a file path on disk spaceRef.fullPath; // Reference's name is the last segment of the full path: "space.jpg" // This is analogous to the file name spaceRef.name; // Reference's bucket is the name of the storage bucket where files are stored spaceRef.bucket;
參考檔案的限制
參照路徑和名稱可包含任何按順序排列的有效 Unicode 字元, 但相關限制設有下列限制:
- 使用 UTF-8 編碼時,reference.fullPath 的總長度必須介於 1 到 1024 個位元組之間。
- 不得使用回車或換行字元。
- 避免使用
#
、[
、]
、*
或?
,因為這些功能無法搭配 其他工具,例如 Firebase Realtime Database 或 gsutil。
完整範例
Swift
// Points to the root reference let storageRef = Storage.storage().reference() // Points to "images" let imagesRef = storageRef.child("images") // Points to "images/space.jpg" // Note that you can use variables to create child values let fileName = "space.jpg" let spaceRef = imagesRef.child(fileName) // File path is "images/space.jpg" let path = spaceRef.fullPath // File name is "space.jpg" let name = spaceRef.name // Points to "images" let images = spaceRef.parent()
Objective-C
// Points to the root reference FIRStorageReference *storageRef = [[FIRStorage storage] reference]; // Points to "images" FIRStorageReference *imagesRef = [storageRef child:@"images"]; // Points to "images/space.jpg" // Note that you can use variables to create child values NSString *fileName = @"space.jpg"; FIRStorageReference *spaceRef = [imagesRef child:fileName]; // File path is "images/space.jpg" NSString *path = spaceRef.fullPath; // File name is "space.jpg" NSString *name = spaceRef.name; // Points to "images" imagesRef = [spaceRef parent];
接著來瞭解 上傳檔案至 Cloud Storage。