火力地堡+斯威夫特：removeAllObservers不工作？

Question

我有2个参考（以相同的路径），一个侦听待办订单和另一个侦听完成的订单。所有用于特定位置，用户可以改变。

我现在使用的机制是这样的：

1. 创建一个阵列，将存储火力地堡引用
2. 之前我observe事件挂单，推那个火力地堡参考到我的数组
3. 之前我observe事件已完成的订单，推动这一火力地堡参考到我的数组
4. 当用户切换自己的位置，删除所有观察员在我的阵列中的所有引用。清空，并启动监听在新位置挂起/已完成订单（步骤2和3）

我的代码如下所示：

struct Firebase { 

    private let ORDERS_PATH = "locations-orders" 

    private static var references = [FIRDatabaseReference]() 

    static func observePendingOrders(lId: String, f: @escaping (AppState.Order) ->()) { 
    print("observing orders for \(ORDERS_PATH)/\(lId)") 

    let pendingOrdersReference = FIRDatabase.database().reference(withPath: "\(ORDERS_PATH)/\(lId)") 
    self.references.append(pendingOrdersReference) 

    pendingOrdersReference 
     .child(dateKeyToday()) 
     .queryOrdered(byChild: "created_at") 
     .observe(.childAdded, with: { firebaseSnapshot in 
     ... 

     print("order received for \(ORDERS_PATH)/\(lId)") 
     } 
    ) 
    } 

    static func fetchCompletedOrders(lId: String, f: @escaping ([AppState.Order]) ->()) { 
    print("observing completed orders for \(lId)") 

    let completedOrdersReference = FIRDatabase.database().reference(withPath: "\(ORDERS_PATH)/\(lId)") 
    self.references.append(completedOrdersReference) 

    completedOrdersReference 
     .child(dateKeyToday()) 
     .queryOrdered(byChild: "status_updated_at") 
     .observe(.value, with: { firebaseSnapshot in 
     ... 
     } 
    ) 
    } 

    static func removeAllOrderObservers() { 
    for reference in references { 
     print("removing reference \(reference)") 
     reference.removeAllObservers() 
    } 
    self.references = [] 
    } 

} 

然而，当我登录订单的位置我正在看的，它看起来像即使我切换位置的老观察员还在听订单。这是我的日志：

observing orders for locations-orders/9RC4H9ZAE457E // first location 
observing completed orders for 9RC4H9ZAE457E 
removing reference https://mydb-123.firebaseio.com/locations-orders/9RC4H9ZAE457E // switch locations, remove all existing observers for location 9RC4H9ZAE457E 
removing reference https://mydb-123.firebaseio.com/locations-orders/9RC4H9ZAE457E 
observing orders for locations-orders/1JS53G0TT5ZQD // start listening for orders in new location. notice the new id: 1JS53G0TT5ZQD 
observing completed orders for 1JS53G0TT5ZQD 
order received for locations-orders/9RC4H9ZAE457E // <-- why is this still showing up? 
order received for locations-orders/1JS53G0TT5ZQD 
order received for locations-orders/1JS53G0TT5ZQD 
order received for locations-orders/9RC4H9ZAE457E // <-- and this one too?? 
order received for locations-orders/1JS53G0TT5ZQD 
order received for locations-orders/1JS53G0TT5ZQD 

===更新=== 我甚至尝试把手，它不工作：

struct Firebase { 

    private static var handles = [UInt]() 
    private static var references = [FIRDatabaseReference]() 

    static func observePendingOrders(lId: String, f: @escaping (AppState.Order) ->()) { 
    print("observing orders for \(ORDERS_PATH)/\(lId)") 

    let pendingOrdersReference = FIRDatabase.database().reference(withPath: "\(ORDERS_PATH)/\(lId)") 
    self.references.append(pendingOrdersReference) 

    let handle = pendingOrdersReference 
     .child(dateKeyToday()) 
     .queryOrdered(byChild: "created_at") 
     .observe(.childAdded, with: { firebaseSnapshot in 
     ... 
     } 
    ) 

    handles.append(handle) 
    } 

    static func fetchCompletedOrders(lId: String, f: @escaping ([AppState.Order]) ->()) { 
    print("observing completed orders for \(ORDERS_PATH)/\(lId)") 

    let completedOrdersReference = FIRDatabase.database().reference(withPath: "\(ORDERS_PATH)/\(lId)") 
    self.references.append(completedOrdersReference) 

    let handle = completedOrdersReference 
     .child(dateKeyToday()) 
     .queryOrdered(byChild: "status_updated_at") 
     .observe(.value, with: { firebaseSnapshot in 
     ... 
     } 
    ) 
    handles.append(handle) 
    } 

    static func removeAllOrderObservers() { 
// for reference in references { 
//  print("removing reference \(reference)") 
//  reference.removeAllObservers() 
// } 
//  
    if !references.isEmpty { 
     let ref = references[0] 
     for handle in handles { 
     print("removing handle \(handle)") 
     ref.removeObserver(withHandle: handle) 
     } 
     self.references = [] 
    } 
    } 
} 

Answer 1

我想我可能已经解决了吗？所以这是因为我确实观察到引用，以便删除所有观察员的父节点没有做任何事情，因为你必须在你观察特定的节点，除去它的子节点上。

let pendingOrdersReference = FIRDatabase 
    .database() 
    .reference(withPath: "\(ORDERS_PATH)/\(lId)") 
    .child(dateKeyToday()) // <---- added this thing 

这是我的最终解决方案，这似乎是工作：

struct Firebase { 
    private static var references = [FIRDatabaseReference]() 

    static func observePendingOrders(lId: String, f: @escaping (AppState.Order) ->()) { 
    print("observing orders for \(ORDERS_PATH)/\(lId)") 

    let pendingOrdersReference = FIRDatabase 
     .database() 
     .reference(withPath: "\(ORDERS_PATH)/\(lId)") 
     .child(dateKeyToday()) 
    self.references.append(pendingOrdersReference) 

    ... 
    } 

    static func fetchCompletedOrders(lId: String, f: @escaping ([AppState.Order]) ->()) { 
    print("observing completed orders for \(ORDERS_PATH)/\(lId)") 

    let completedOrdersReference = FIRDatabase 
     .database() 
     .reference(withPath: "\(ORDERS_PATH)/\(lId)") 
     .child(dateKeyToday()) 
    self.references.append(completedOrdersReference) 

    ... 

    } 

    static func removeAllOrderObservers() { 
    for reference in references { 
     print("removing reference \(reference)") 

     reference.removeAllObservers() 
    } 
    self.references = [] 
    } 

}