您的文件存儲在Cloud Storage 存儲桶中。此存儲桶中的文件以層次結構呈現,就像本地硬盤上的文件系統或 Firebase 實時數據庫中的數據一樣。通過創建對文件的引用,您的應用程序可以訪問它。這些引用隨後可用於上傳或下載數據、獲取或更新元數據或刪除文件。引用可以指向特定文件或層次結構中的更高級別節點。
如果您使用過Firebase Realtime Database ,這些路徑對您來說應該非常熟悉。但是,您的文件數據存儲在 Cloud Storage 中,而不是實時數據庫中。
創建參考
創建引用以上傳、下載或刪除文件,或者獲取或更新其元數據。可以將引用視為指向雲中文件的指針。引用是輕量級的,因此您可以根據需要創建任意數量的引用。它們也可重複用於多種操作。
引用是使用FirebaseStorage
服務並調用其reference
方法創建的。
迅速
// 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()
目標-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];
您可以通過對現有引用使用child
方法來創建對樹中較低位置的引用,例如'images/space.jpg'
。
迅速
// 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)
目標-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"];
使用參考導航
您還可以使用parent
和root
方法在我們的文件層次結構中向上導航。 parent
向上導航一個級別,而root
一直導航到頂部。
迅速
// 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()
目標-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
可以多次鏈接在一起,因為每個都返回一個引用。例外是root
的parent
,即nil
。
迅速
// 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()
目標-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];
參考屬性
您可以使用fullPath
、 name
和bucket
屬性檢查引用以更好地了解它們指向的文件。這些屬性獲取文件的完整路徑、名稱和存儲桶。
迅速
// 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
目標-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;
參考文獻的限制
引用路徑和名稱可以包含任何有效的 Unicode 字符序列,但有一定的限制,包括:
- 使用 UTF-8 編碼時,reference.fullPath 的總長度必須在 1 到 1024 字節之間。
- 沒有回車符或換行符。
- 避免使用
#
、[
、]
、*
或?
,因為這些不能很好地與其他工具(例如Firebase 實時數據庫或gsutil)一起使用。
完整示例
迅速
// 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()
目標-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];
接下來,讓我們學習如何將文件上傳到雲存儲。