Question

我刚开始使用Swift / firebase，对不起，我很抱歉。我正在使用childbyautoid将数据写入Firebase数据库。我想访问另一个类中的最后一个键/ ID。

    let postName = Database.database().reference().child("Event").childByAutoId()

    let postNameObject = [
        "EventName": NameTextField.text,
        "timestamp": [".sv":"timestamp"],
        "userID": Auth.auth().currentUser!.uid
    ] as [String:Any]

    postName.setValue(postNameObject, withCompletionBlock: { error, ref in
        if error == nil {
            self.dismiss(animated: true, completion: nil)
        } else {
        }
    })
    let childautoID = postName.key

我希望能够在另一个类中调用childautoID，我们找到了另一种更新此节点的方法。

Answer 1

您也许可以创建一个用于管理Firebase方法的单例类。每当使用Firebase构建应用程序时，我都会做类似的事情。这样，您可以跨多个类引用值并全局使用与Firebase相关的方法。在采用这种方法之前，我发现自己重写了用于将对象上传到Firebase的相同代码。单例可让您创建可重用的代码，包括存储此全局类中设置的“最后一个键”。

class FirebaseManager {

    //You've probably seen something similar to this "shared" in other Apple frameworks
    //Maybe URLSession.shared or FileManager.default or UserDefaults.standard or SKPaymentQueue.default() or UIApplication.shared
    static var shared = FirebaseManager()

    func createEvent(name: String, timeStamp: [String:String], uid: String) {
        let postNameObject = [
            "EventName": name,
            "timestamp": timeStamp,
            "userID": uid
        ] as [String:Any]

        postName.setValue(postNameObject, withCompletionBlock: { error, ref in
            if error == nil {
                self.dismiss(animated: true, completion: nil)
            } else {
                //Do something
            }
        })
        let childautoID = postName.key

        //Whatever else you need to do in the function below here...

    }

}

用法：

class SomeViewController: UIViewController {

    @IBOutlet var nameTextField: UITextField!

    //Some code...

    @IBAction func createEventButtonPressed(_ sender: Any) {
        FirebaseManager.shared.createEvent(name: nameTextField.text, timeStamp: [".sv":"timestamp"], uid: Auth.auth().currentUser!.uid)
    }

    //Some more code...
}

类似地，您可以在我们的lastKey类中添加一个类型为String的名为FirebaseManager的值。请注意，我们添加到FirebaseManager类顶部的变量：

class FirebaseManager {

    var lastKey: String!

    static var shared = FirebaseManager()

    func createEvent(name: String, timeStamp: [String:String], uid: String) {
        let postNameObject = [
            "EventName": name,
            "timestamp": timeStamp,
            "userID": uid
        ] as [String:Any]

        postName.setValue(postNameObject, withCompletionBlock: { error, ref in
            if error == nil {
                self.dismiss(animated: true, completion: nil)
            } else {
                //Do something
            }
        })
        let childautoID = postName.key

        //Whatever else you need to do in the function below here...

    }

}

类似地，我们可以在一个视图控制器中设置该值：

class ViewControllerA: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        FirebaseManager.shared.lastKey = "aBcDeFg9876543210"
    }
}

并在另一个加载前一个视图控制器的视图控制器中获取此值：

class ViewControllerB: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        print(FirebaseManager.shared.lastKey)
    }
}

打印：aBcDeFg9876543210

这是static关键字的美。您可以在此处了解有关创建单例类的更多信息：https://cocoacasts.com/what-is-a-singleton-and-how-to-create-one-in-swift

如何获得在另一个类的一个类中声明的变量？

1 个答案: