Question

我正在尝试获取Firebase数据库中所有用户帖子的第一张图片，但是代码仅在第一位用户的帖子中运行，然后对于所有其他用户，它不会运行下面的代码块：含义为如果让为零，那我该如何解决呢？

更新我已经确定该错误发生在let imageDataL = try? Data(contentsOf: imageUrl!)上，但是不确定如何更改它以使其正常工作。只能运行一次的块：

if let imageUrlString = i.value as? [String:AnyObject], let postUrl = imageUrlString["image1"] as? String {
    print("Description: inside the if let imageUrlString = i.value ")

    self.feedArray.append(Post(fetchedImageURL: postUrl))
    if let imageUrl = URL(string: postUrl), let imageDataL = try? Data(contentsOf: imageUrl), let image = UIImage(data: imageDataL) {
        print("Description: inside the if let imageUrl = URL(string: postUrl)")
        print("Description: img url's of posts: \(imageUrl)")
        self.tableData.append(UserImage(image: image, postNum: p.key, userID: user))
        self.tableView.reloadData()
    } else {print("users had no posts, was nil")}
}

全功能：

func fetchAllUserFristImage() {
print("Description: calling of fetchAllUserFristImage()")
Database.database().reference().child("Posts").observe(.childAdded, with: {(snapshot) in

    if snapshot.value as? [String: AnyObject] != nil {
        let user = snapshot.key
        print("Description: calling of snapshot.value is not nil ")

        self.databaseRef = Database.database().reference()

        let usersPostRef2 = self.databaseRef.child("Posts").child(user)

        usersPostRef2.observe(.value, with: {(postXSnapshots) in

            if let postDictionary2 = postXSnapshots.value as? [String:AnyObject] {

                for (p) in postDictionary2 {

                    if let posts = p.value as? [String:AnyObject] {
                        print("Description: posts has value of:  \(posts)")

                        //to get back to where i was delete the below for i
                        for (i) in posts {

                            if let imageUrlString = i.value as? [String:AnyObject], let postUrl = imageUrlString["image1"] as? String {
                                print("Description: inside the if let imageUrlString = i.value ")

                                self.feedArray.append(Post(fetchedImageURL: postUrl))
                                if let imageUrl = URL(string: postUrl), let imageDataL = try? Data(contentsOf: imageUrl), let image = UIImage(data: imageDataL) {
                                    print("Description: inside the if let imageUrl = URL(string: postUrl)")
                                    print("Description: img url's of posts: \(imageUrl)")
                                    self.tableData.append(UserImage(image: image, postNum: p.key, userID: user))
                                    self.tableView.reloadData()
                                } else {print("users had no posts, was nil")}
                            }
                        }
                    }
                }
            }
        })
        //below shud stay same
        DispatchQueue.main.async {
            self.tableView.reloadData()
        }
    }
})

}

我的数据库结构：

    {
  "Posts" : {
    "7AM0CeJ71tYON9NejziFZto16fk2" : {
      "post1" : {
        "ImageUrl" : {
          "image1" : "https://URLHere",
          "image2" : "https://URLHere"
        }
      }
    },
    "Q4qiUCjN5bNXdPkrzYMQFGe79oH3" : {
      "post1" : {
        "ImageUrl" : {
          "image1" : "https://URLHere",
          "image2" : "https://URLHere"
        }
      }
    }
  },
  "users" : {
    "7AM0CeJ71tYON9NejziFZto16fk2" : {
      "email" : "dhhfhfhffhdh@hdhdhdjdh.hehdhdhdh",
      "password" : "dhdhdhhdhdhdhdhdhfhf"
    },
    "9S9W4EM52PZn23smnhNytOWvvIt2" : {
      "email" : "hdhddhhddhdh@hdhddhdh.hedhhdhddyd",
      "password" : "dhdhdhhdhdhdhdhdhf"
    },
    "B3DnljxZMmXd5Hrq1qTKQl08s1a2" : {
      "email" : "fhfhfhhfhfhf@3737476446.38384747",
      "password" : "hehdhdhfhdhfhfhfhdhdhdhdhdhdhdhdhf"
    },
    "DuLp2XUBkkbQ223JHwmN6nzJR942" : {
      "email" : "hrhdhdhdfhfh@hdhddhdh.hdhdhf",
      "password" : "ddhdhhddjhfhfg"
    },
    "Q4qiUCjN5bNXdPkrzYMQFGe79oH3" : {
      "email" : "nehdhdhdhddhfh@hddhdhdh.hdhdhdh",
      "password" : "dhhdhdhfhdhdhfhfhdfb"
    },
  }
}

Answer 1

以下代码将遍历Posts中的子节点，为每个帖子打印uid，然后为每个帖子打印图像名称和url。请注意var self 指向我的Firebase。

func fetchAllUsersImages() {
    self.ref.child("Posts").observe(.childAdded, with: { snapshot in
        let uid = snapshot.key
        let postSnap = snapshot.childSnapshot(forPath: "post1")
        let imageUrlSnap = postSnap.childSnapshot(forPath: "ImageUrl")
        guard let allImages = imageUrlSnap.children.allObjects as? [DataSnapshot] else { return }
        for url in allImages {
            let imageName = url.key
            let path = url.value as! String
            print(uid, imageName, path)
        }
        print()
    })
}

以及基于您的结构的输出

7AM0CeJ71tYON9NejziFZto16fk2 image1 https://URLHere
7AM0CeJ71tYON9NejziFZto16fk2 image2 https://URLHere

Q4qiUCjN5bNXdPkrzYMQFGe79oH3 image1 https://URLHere
Q4qiUCjN5bNXdPkrzYMQFGe79oH3 image2 https://URLHere

仅检索了1个用户的图像。迅捷，Firebase

1 个答案: