uploading/downloading 多张图片的正确方式？

Question

我正在尝试使用 Nuke（用于下载和缓存图像的框架）和 Firebase 上传或下载图像以将图像上传为后端

对于单个文件很容易处理没有任何问题但对于多个人我真的不知道该怎么做我有一个问题，它不能同步工作它有时会在第一张图片之前下载第二张图片

我将展示我下载和上传多张图片的方法

为了下载，我把代码放在 for-loop

    func downloadImages(completion: (result: [ImageSource]) -> Void){
    var images = [ImageSource]()
    for i in 0...imageURLs.count-1{

        let request = ImageRequest(URL: NSURL(string:imageURLs[i])!)

        Nuke.taskWith(request) { response in
            if response.isSuccess{
        let image = ImageSource(image: response.image!)
                images.append(image)
                if i == self.imageURLs.count-1 {
                    completion(result: images)
                }
            }


        }.resume()


    }

}

并在用户选择图片的地方上传形成图像选择器并将其 return 作为 NSData 数组然后执行这段代码

    func uploadImages(completion: (result: [String]) -> Void){
    let storageRef = storage.referenceForURL("gs://project-xxxxxxxxx.appspot.com/Uploads/\(ref.childByAutoId())")
    var imageUrl = [String]()
    var imgNum = 0



    for i in 0...imageData.count-1 {
        let imagesRef = storageRef.child("\(FIRAuth.auth()?.currentUser?.uid) \(imgNum)")
        imgNum+=1

        let uploadTask =  imagesRef.putData(imageData[i], metadata: nil) { metadata, error in
            if (error != nil) {
                print("error")
                imageUrl = [String]()
                completion(result: imageUrl)
            } else {

                print("uploading")
                // Metadata contains file metadata such as size, content-type, and download URL.
                let downloadURL = metadata!.downloadURL()?.absoluteString
                print(downloadURL)
                imageUrl.append(downloadURL!)
                if i == imageUrl.count-1{ //end of the loop
                    print("completionUpload")
                    completion(result: imageUrl)

                }
            }
        }}

这是完成这项任务的好方法吗？

我应该怎么做才能让每张图片按顺序下载？

请给我任何可能对示例代码有帮助的东西，link 等 ..

提前致谢

Answer 1

我们强烈建议同时使用 Firebase 存储和 Firebase 实时数据库来完成下载列表：

已分享：

// Firebase services
var database: FIRDatabase!
var storage: FIRStorage!
...
// Initialize Database, Auth, Storage
database = FIRDatabase.database()
storage = FIRStorage.storage()

上传：

let fileData = NSData() // get data...
let storageRef = storage.reference().child("myFiles/myFile")
storageRef.putData(fileData).observeStatus(.Success) { (snapshot) in
  // When the image has successfully uploaded, we get it's download URL
  let downloadURL = snapshot.metadata?.downloadURL()?.absoluteString
  // Write the download URL to the Realtime Database
  let dbRef = database.reference().child("myFiles/myFile")
  dbRef.setValue(downloadURL)
}

下载：

let dbRef = database.reference().child("myFiles")
dbRef.observeEventType(.ChildAdded, withBlock: { (snapshot) in
  // Get download URL from snapshot
  let downloadURL = snapshot.value() as! String

  // Now use Nuke (or another third party lib)
  let request = ImageRequest(URL: NSURL(string:downloadURL)!)
  Nuke.taskWith(request) { response in
    // Do something with response
  }

  // Alternatively, you can use the Storage built-ins:
  // Create a storage reference from the URL
  let storageRef = storage.referenceFromURL(downloadURL)
  // Download the data, assuming a max size of 1MB (you can change this as necessary)
  storageRef.dataWithMaxSize(1 * 1024 * 1024) { (data, error) -> Void in
    // Do something with data...
  })
})

有关详细信息，请参阅 Zero to App: Develop with Firebase, and it's associated source code，了解如何执行此操作的实际示例。

uploading/downloading 多张图片的正确方式？

uploading/downloading multiple images the right way?

ios

firebase

swift

firebase-storage