Swift 4 Firebase 在线状态更新

Question

我构建了聊天应用程序。我在每个用户表中都有允许检查用户是否在线的字段。我只使用数据库引用来获取 isOnline 状态并在拉动刷新时更新它。我看到当用户打开或折叠应用程序时，应用程序会自动更新在线状态。我怎么能这样做？我需要任何监听器或任何框架可以帮助我升级我的代码））像 ReactiveCocoa/ReactiveSwift 之类的东西......

P.S 对不起字段 isOnline 上的西里尔文字）这意味着在线/离线

Answer 1

当应用启动时，您可以在 AppDelegate 中在线更新用户

在线更新用户

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

        FirebaseApp.configure()
        // status parameter indicate user Online
        if Auth.auth().currentUser != nil {
            OnlineOfflineService.online(for: (Auth.auth().currentUser?.uid)!, status: true){ (success) in

                print("User ==>", success)

            }
        }
        return true
    }

离线更新用户

func applicationWillTerminate(_ application: UIApplication) {
        if Auth.auth().currentUser != nil {
            OnlineOfflineService.online(for: (Auth.auth().currentUser?.uid)!, status: false){ (success) in

                print("User ==>", success)
            }
        }
 }

Firebase 在线和离线更新服务

import UIKit
import FirebaseDatabase

struct OnlineOfflineService {
    static func online(for uid: String, status: Bool, success: @escaping (Bool) -> Void) {
        //True == Online, False == Offline
        let onlinesRef = Database.database().reference().child(uid).child("isOnline")
        onlinesRef.setValue(status) {(error, _ ) in

            if let error = error {
                assertionFailure(error.localizedDescription)
                success(false)
            }
            success(true)
        }
    }
}

您还需要注意用户网络连接。如果用户网络连接断开，您只需使用参数调用OnlineOfflineService

Answer 2

我知道这是一个较老的问题，但如果您想在用户关闭应用时将在线/离线值设置为 false，请使用 .onDisconnectSetValue()：

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    FirebaseApp.configure()

    setInactivityObservers()

    return true
}

func setInactivityObservers() {
    guard let user = Auth.auth().currentUser else { return }

    // get user branch of database
    let ref = Database.database().reference()
    let usersRef = ref.child("Users")
    let userRef = usersRef.child(user.uid)

    // set "isOnline" branch to true when app launches
    userRef.child("isOnline").setValue(true)

    // set value to false when user terminates app
    userRef.child("isOnline").onDisconnectSetValue(false)
}

Answer 3

第一

Database.database().isPersistenceEnabled = true

然后管理“存在”

let presenceRef = Database.database().reference(withPath: "disconnectmessage");
// Write a string when this client loses connection
presenceRef.onDisconnectSetValue("I disconnected!")

然后当用户断开连接时

presenceRef.onDisconnectRemoveValue { error, reference in
  if let error = error {
    print("Could not establish onDisconnect event: \(error)")
  }
}

最后，检测状态

let connectedRef = Database.database().reference(withPath: ".info/connected")
connectedRef.observe(.value, with: { snapshot in
  if snapshot.value as? Bool ?? false {
    print("Connected")
  } else {
    print("Not connected")
  }
})

现在可以了吗？