ios - 获取存储在Firebase中的数据值

我试图访问存储在Firebase仪表板中的值，以在类中的不同函数和方法中使用它们。

I used this method in this question

我试图打印它们的值，整个应用程序崩溃了，这给了我他们零！

他们实际上不是零！
我在viewDidLoad中使用了类似的方法，并且可以将值检索到标签！

let refer = FIRDatabase.database().reference().child("UserDevices")

var globalEmail : String!
var globalPhone : String!
var globalImageUrl: String!


override func viewWillAppear(_ animated : Bool){
    super.viewWillAppear(animated)
    retrieveUserData{(email,phone,ImageUrl) in
        self.globalEmail = email
        self.globalPhone = phone
        self.globalImageUrl = ImageUrl
    }

}

func retrieveUserData(_ completionBlock : @escaping ((_ email : String?, _ phone : String?, _ ImageUrl: String?)->Void)){
    refer.child(byAppendingPath: self.strUserid as String).observe(.value , with: {snapshot in
        if let userDict =  snapshot.value as? [String:AnyObject]  {
            completionBlock(userDict["email"] as! String, userDict["phone"] as! String, userDict["ImageUrl"] as! String)
        }
    })
}

var strUserid : NSString!
override func viewDidLoad() {
    super.viewDidLoad()

    print(globalEmail)
    print(globalImageUrl)
    print(globalPhone)

    self.navigationController?.navigationBar.tintColor = UIColor.white

    print("idis \(self.strUserid)")

     let ref = FIRDatabase.database().reference().child("UserDevices")

     self.navigationController?.navigationBar.tintColor = UIColor.white
    ref.child(byAppendingPath: self.strUserid as String).observe(.value, with: { snapshot in

        if let dict = snapshot.value as? NSMutableDictionary{

            print("dict is \(dict)")

            if let Provider = dict["name"] as? String
            {
                self.DeviceDetailsProvider.text = Provider
               // self.navigationItem.title = Provider
            }
            if let name = dict["DeviceName"] as? String
            {
                self.DeviceDetailsName.text = name
                self.navigationItem.title = name
            }
            if let ShortDescription = dict["Description"] as? String
            {
                self.DeviceDetailsDescription.text = ShortDescription
            }
            if let City = dict["city"] as? String
            {
                self.DeviceDetailsCity.text = City
            }

        }
    })


   self.DeviceDetailsImageView.downloadedFrom(link: globalImageUrl)

}

为什么我在这里撞车！

最佳答案

更改ref.child(byAppendingPath: self.strUserid as String)

至：-

ref.child(self.strUserid)

同时删除let refer = FIRDatabase.database().reference().child("UserDevices")。

您无法在范围外全局初始化您的引用，因为您不知道类的初始化顺序，并且可能的情况是，当您尝试初始化let refer时，甚至还没有初始化FIRDatabase。

代替在refer中使用retrieveUserData

FIRDatabase.database().reference().child("UserDevices")

您可以在viewController的LIFE CYCLE中看到，viewdidLoad在viewWillAppear之前被调用：

因此，您需要的是：-

override func viewDidLoad() {
 super.viewDidLoad()
  ..
   retrieveUserData{(email,phone,ImageUrl) in
    self.globalEmail = email
    self.globalPhone = phone
    self.globalImageUrl = ImageUrl
     self.DeviceDetailsImageView.downloadedFrom(link: globalImageUrl)
    // .. Do your stuff...

       }

  }

读取：Viewcontroller's Lifecycle