xcode 从新的 Firebase 检索数据

Retrieve data from new Firebase

提问by Dmitry Kuzin

Please help. After migrating to new Firebase I can't retrieve data. Use this construction:

请帮忙。迁移到新 Firebase 后，我无法检索数据。使用这个结构：

let ref = FIRDatabase.database().reference()

override func viewDidLoad() {
    super.viewDidLoad()
    ref.observeEventType(FIRDataEventType.Value, withBlock: { (snapshot) in
        let postDict = snapshot.value as! [String : AnyObject]
        print("\(postDict)")
    })
}

After running I see error:

运行后我看到错误：

2016-05-19 10:04:22.264 123a[88652:13688922] The default app has not been configured yet.
2016-05-19 10:04:22.276 123a[88652:13688922] *** Terminating app due to uncaught exception 'MissingDatabaseURL', reason: 'Failed to get FIRDatabase instance: FIRApp object has no databaseURL in its FirebaseOptions object.'
*** First throw call stack:

I read documentation, but can't resolve this problem. GoogleService-Info.plist I add to project.

我阅读了文档，但无法解决此问题。我添加到项目中的 GoogleService-Info.plist。

回答by Tom Wolters

I didn't see this answer yet, I had to add the configure call to the AppDelegate init method. So it looks like:

我还没有看到这个答案，我不得不将配置调用添加到 AppDelegate init 方法。所以它看起来像：

override init() {
    super.init()
    // Firebase Init
    FIRApp.configure()
}

回答by Ugur

Had the same problem. I looked for linking problems that are related to the plist but that wasn't the problem. I thought maybe it has caused because of that my initial view controller is revoked before the configurations are completed. I solved the problem by experimenting a bit.

有同样的问题。我寻找与 plist 相关的链接问题，但这不是问题。我想可能是因为我的初始视图控制器在配置完成之前被撤销了。我通过一些实验解决了这个问题。

My initial view controller was this:

我最初的视图控制器是这样的：

    let ref = FIRDatabase.database().reference()

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

}

I've changed that to this:

我把它改成这样：

    var ref = FIRDatabaseReference.init()

override func viewDidLoad() {
    super.viewDidLoad()
    ref = FIRDatabase.database().reference()

    // Do any additional setup after loading the view, typically from a nib.

}

Crash resolved.

崩溃解决。

回答by ColdLogic

So, with mine, I also had a ref being declared immediately when the view controller was instantiated. I had to make it load after the app had been configured in the app delegate with FIRApp.configure().

所以，对于我的，当视图控制器被实例化时，我也立即声明了一个 ref。在应用程序委托中使用FIRApp.configure().

Before:

前：

let serverRef = Firebase("firebaseURL")

After:

后：

lazy var serverRef = FIRDatabase.database().reference()

This delays the instantiation of the database reference until its needed, which wont be until viewDidLoadon your initial view controller.

这将数据库引用的实例化延迟到需要时，直到viewDidLoad您的初始视图控制器上才需要。

回答by JiuJitsuCoder

To build on the answer given by @ColdLogic, the reason I had this error was because I had my Firebase database reference being created in an init method on a view controller, notin the viewDidLoad method. Since the init methods for all classes that are instantiated when the app launches are called beforethe application:DidFinishLaunchingWithOptions method in the AppDelegate, it was causing this crash. Moving this line of code:

为了建立在@ColdLogic 给出的答案的基础上，我出现此错误的原因是我的 Firebase 数据库引用是在视图控制器的 init 方法中创建的，而不是在 viewDidLoad 方法中。由于在应用程序启动时实例化的所有类的 init 方法是在 AppDelegate 中的 application:DidFinishLaunchingWithOptions 方法之前调用的，因此导致了此崩溃。移动这行代码：

class MyViewController {

   var firebaseRef: FIRDatabaseReference

   required init?(coder aDecoder: NSCoder) {
      ...
      firebaseRef = FIRDatabase.database().reference()
   }

   override func viewDidLoad() {
      ...
   }
}

to here:

到这里：

class MyViewController {

   var firebaseRef: FIRDatabaseReference

   required init?(coder aDecoder: NSCoder) {
      ...
   }

   override func viewDidLoad() {
      ...
      self.firebaseRef = FIRDatabase.database().reference()
   }
}

solved the problem for me.

为我解决了这个问题。

回答by Markinson

I too had a problem with the Firebase Database. Fixed it by adding

我也遇到了 Firebase 数据库的问题。通过添加修复它

import FirebaseDatabase

to my code

到我的代码

回答by enc_life

I was getting this error until I made FIRApp.configure()the first line in the AppDelegatedidFinishLaunchingWithOptions

我收到此错误，直到我FIRApp.configure()在AppDelegatedidFinishLaunchingWithOptions

回答by Tiago Almeida

In my case I had to change the configure to be called before calling the super applicationDidLaunch:

就我而言，我必须在调用超级 applicationDidLaunch 之前更改要调用的配置：

[FIRApp configure];

[super application:application didFinishLaunchingWithOptions:launchOptions];

回答by Jan Hartwig

Had the same problem today, you need the "firebase_url": "https://xxxxxxxxxx.firebaseio.com" at google-services.json and for that do this steps https://support.google.com/firebase/answer/7015592#androidIf you had one file from google cloud platform before, maybe there are some differences and you have to check. For me this works.

今天遇到了同样的问题，您需要在 google-services.json 上使用“firebase_url”：“ https://xxxxxxxxxx.firebaseio.com”，为此请执行以下步骤https://support.google.com/firebase/answer/ 7015592#android如果你之前有一个来自谷歌云平台的文件，可能有一些差异，你必须检查一下。对我来说这是有效的。

回答by Junaid Mukhtar

Make sure you have downloaded the GoogleService-Info.plistfile from your Firebase console and added to the root of your project directory.

确保您GoogleService-Info.plist已从 Firebase 控制台下载该文件并将其添加到项目目录的根目录中。

Once you have added it call this function from didFinishLaunchingWithOptionsin AppDelegate:

添加后，它会从didFinishLaunchingWithOptionsAppDelegate 中调用此函数：

FIRApp.configure()

Thats it, it should be up and running!

就是这样，它应该启动并运行！