等待图片上传后再继续功能 - Swift 5 Firebase Storage

Question

我正在尝试使用 Firebase 存储上传图片。我遇到的问题是，当我调用图像上传函数时，上传任务非常慢，当它实际上被进一步调用时，它最终在我的主函数中最后运行。

有没有办法等待 storageRef.putData 完成，然后再继续函数的其余部分？

压缩质量从 1 降低会更快吗？

这是我的函数：

func newImageUrl(){
    let key = self.itemId
    guard let userID = Auth.auth().currentUser?.uid else { return }
    let storageRef = Storage.storage().reference().child(userID).child("SubCategory").child(self.itemTitle!).child(key!).child("ItemImages.jpg")
    guard let imageData = self.itemImage.image!.jpegData(compressionQuality: 1) else { return }
    print("starting image upload!")
    storageRef.putData(imageData, metadata: nil) { (metadata, error) in
        guard let metadata = metadata else {
            return
        }
        storageRef.downloadURL { (url, error) in
            guard let urlStr = url else{
                return
            }
                let urlFinal = (urlStr.absoluteString)
                self.imageFinalUrl = urlFinal
        }
    }
}

更新的功能 --

func newImageUrl(completion:@escaping((String?) -> () )) {
let key = self.itemId
guard let userID = Auth.auth().currentUser?.uid else { completion(nil) ; return }
let storageRef = Storage.storage().reference().child(userID).child("SubCategory").child(self.itemTitle!).child(key!).child("ItemImages.jpg")
guard let imageData = self.itemImage.image!.jpegData(compressionQuality: 1) else { completion(nil) ; return }
print("starting image upload!")
storageRef.putData(imageData, metadata: nil) { (metadata, error) in
    guard let metadata = metadata else {
        return
    }
    storageRef.downloadURL { (url, error) in
        guard let urlStr = url else{
            completion(nil)
            return
        }
        let urlFinal = (urlStr.absoluteString)
        self.imageFinalUrl = urlFinal
        completion(urlFinal)
        }
    }
}

示例主函数：

func updateItemDetail(){
    print("this is running 1")
    self.newImageUrl { (str) in
        print(str)
    }
    print("this is running 2")

控制台打印：

this is running 1
starting image upload!
this is running 2
Optional("https://firebasestorage.googleapis.com/v0/b/.....etc")

Answer 1

你需要一个完成

func newImageUrl(completion:@escaping((String?) -> () )) {
    let key = self.itemId
    guard let userID = Auth.auth().currentUser?.uid else { completion(nil) ; return }
    let storageRef = Storage.storage().reference().child(userID).child("SubCategory").child(self.itemTitle!).child(key!).child("ItemImages.jpg")
    guard let imageData = self.itemImage.image!.jpegData(compressionQuality: 1) else { completion(nil) ; return }
    print("starting image upload!")
    storageRef.putData(imageData, metadata: nil) { (metadata, error) in
        guard let metadata = metadata else {
            return
        }
        storageRef.downloadURL { (url, error) in
            guard let urlStr = url else{
                completion(nil)
                return
            }
            let urlFinal = (urlStr.absoluteString)
            self.imageFinalUrl = urlFinal
            completion(urlFinal)
        }
    }
}

---

叫

newImageUrl { (str) in
  print(str)
  // do your next work here
}