Question

编辑（我希望这是更具体的）：

当我运行应用程序时，我似乎无法从Firebase获取数据来显示页面：

将通知保存在firebase的子节点下时，将打印'objectId'-我想在另一个名为“ pinion”的节点（JSON firebase结构的代码段）下获取与此objectId匹配的节点下的数据是：

"notification" : {
    "Gmg1ojNoBiedFPRNSL4sBZz2gSx2" : {
      "-L_xNVcs7f3RhuLAcg7j" : {
        "from" : "Gmg1ojNoBiedFPRNSL4sBZz2gSx2",
        "objectId" : "-L_xNVcfZavjGFVv6iGs",
        "timestamp" : 1552586771,
        "type" : "pinion"
      },
"pinions" : {
    "Gmg1ojNoBiedFPRNSL4sBZz2gSx2" : {
      "-L_xNVcfZavjGFVv6iGs" : {
        "option A" : "Aaaa",
        "option B" : "Cccc",
        "question" : "Four",
        "selectedId" : "FoFQDAGGX9hntBiBdXYCBHd8yas2",
        "uid" : "Gmg1ojNoBiedFPRNSL4sBZz2gSx2"
      },
  "users" : {
    "Gmg1ojNoBiedFPRNSL4sBZz2gSx2" : {
      "email" : "eeee@gmail.com",
      "fullname" : "Eeee",
      "profileImageUrl" : "https://firebasestorage.googleapis.com/v0/b/pinion-4896b.appspot.com/o/profile_image%2FGmg1ojNoBiedFPRNSL4sBZz2gSx2?alt=media&token=209e57ca-b914-4023-8f85-fadfae7b7407",
    },

非常感谢您的帮助，如果您需要其他任何信息，请告诉我-提前谢谢：）

更新：

它适用于问题和答案，但是调用图像时出现错误“无法在当前上下文中推断闭包类型”：

@IBOutlet weak var senderProfileImage: UIImageView!

override func viewDidLoad() {
    super.viewDidLoad()
    showImageOfSender()
}
var ref = Database.database().reference()
var userId = "" //this was made equal to the autoId under pinion, under the users ID in another view controller

 func showImageOfSender() {
    var senderPhoto = [String]()
    guard let uid = Auth.auth().currentUser?.uid else {
        return
    }

   let senderId = ref.child("pinions").child(uid).child(userId).child("uid")
        ref.child("users").child(senderId).observeSingleEvent(of: .value, with: { snapshot in
 //error is in the above line
        let senderImage = snapshot.childSnapshot(forPath: "profileImageUrl").value as! String
        senderPhoto.append(senderImage)

        let senderImageUrl = URL.init(string: senderImage)
        self.senderProfileImage.sd_setImage(with: senderImageUrl)
    })
}

Answer 1

我想这就是您的意思，首先导入Firebase：

  import Firebase

然后获取数据库引用：

  class PinionNotificationsViewController: UIViewController {

   var ref: DatabaseReference!

   ...

   }

然后，如果您知道UID，则函数可以如下所示：

func showQuestionAndAnswers() {

let uid = userId
ref = ref.child("pinions").child(uid)

ref.observeSingleEvent(of: .value, with: { (snapshot) in
        // Get user value
        let value = snapshot.value as? NSDictionary
        let optionA = value?["option A"] as! String
        let optionB = value?["option B"] as! String
        print(optionA) // <- prints: "Bbbb"
        print(optionB) // <- prints: "Dddd"

    })
 }

如果您不知道uid，就可以使用

ref = ref.child("pinions")
ref.observe(.childAdded) { (snapshot) in
        // Get user value
        let value = snapshot.value as? NSDictionary
        let optionA = value?["option A"] as! String
        // then you can append these values into an array it will go through all of them eg:
         self.answersArray.append(optionA) // answers array will contain all optionA values from all children in the database under `"pinions"`

    }

根据我的经验，这种方式将匹配数据库的顺序，因此在您的数组中，所有选项将按照其子级的顺序，就像它们在数据库中的顺序一样。

希望这会有所帮助！

抓取保存在Firebase中的数据并将其显示在视图控制器上

1 个答案: