swift - 在for循环中附加图像url数组，然后发布到数据库

Question

我对快速开发有点陌生，并且遇到了一个问题。我有一个 UIImages 数组，我正在运行 for 循环来创建 URL 并使用 firebase 进行存储。图像正确存储在我的 firebase 存储中，但我目前在创建包含给定图像的 URL 的帖子时遇到问题。

正确的帖子应包含 itemName、itemPrice、用户名、imageA 和 imageB。我现在的方式是它创建了 2 个帖子，我理解它是因为它在 for 循环中，并且它将对两个图像迭代两次，但是我一直在思考如何在迭代 for 后使用两个图像创建一个帖子循环存储图像。

     @IBAction func confirmAction(_ sender: Any) {

    var uploadedImageUrlsArr = [String]()


    for image in imageArr{
        let imageName = NSUUID().uuidString
        let storageRef = Storage.storage().reference().child("Advertisement_Images_Main").child("\(imageName).png")

        let myImage = image
        guard let uploadData  = UIImagePNGRepresentation(myImage) else {
            return
        }
        storageRef.putData(uploadData, metadata: nil, completion: { (metadata, error) in

            if let error = error {
                print(error)
                return
            }
            if let imageURL = metadata?.downloadURL()?.absoluteString{
                print (imageURL)
                uploadedImageUrlsArr.append(imageURL)
                let post : [String : AnyObject] = ["item" : self.itemNameTextField.text as AnyObject, "price" : self.itemPriceTextField.text as AnyObject, "username": self.username as AnyObject, "imageA": imageURL as AnyObject]
                self.ref?.child("Items").childByAutoId().setValue(post)

            }



        })
    }

  //  let post : [String : AnyObject] = ["item" : self.itemNameTextField.text as AnyObject, "price" : self.itemPriceTextField.text as AnyObject, "username": self.username as AnyObject, "imageA": imageURL as AnyObject]

    self.performSegue(withIdentifier: "confirmedSegue", sender: nil)
}

Answer 1

由于 storageRef.putData(... 是一个异步调用，因此您需要等待两个图像的响应才能同时发布两个图像，所以我认为您可以对代码进行这些更改以实现您想要的行为:

        if let imageURL = metadata?.downloadURL()?.absoluteString{
              print (imageURL)
              uploadedImageUrlsArr.append(imageURL)
              if uploadedImageUrlsArr.count == 2 { //you can use self.imageArr.count instead of 2 {
                let post : [String : AnyObject] = ["item" : self.itemNameTextField.text as AnyObject, "price" : self.itemPriceTextField.text as AnyObject, "username": self.username as AnyObject, "imageA": uploadedImageUrlsArr[0] as AnyObject, "imageB": uploadedImageUrlsArr[1] as AnyObject]

                self.ref?.child("Items").childByAutoId().setValue(post)
              }
        }