我有 2 个引用(指向同一路径),一个用于监听挂单,另一个用于监听已完成的订单。全部针对特定位置,用户可以更改该位置。
我现在使用的机制是这样的:
- 创建一个用于存储 Firebase 引用的数组
- 在
观察
挂单事件之前,将该 Firebase 引用推送到我的数组中 - 在
观察
已完成订单的事件之前,将该 Firebase 引用推送到我的数组中 - 当用户切换位置时,删除数组中所有引用的所有观察者。清空数组并开始监听新位置中的待处理/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 = []
}
}
但是,当我记录我正在监视的订单的位置时,看起来即使在我切换位置后,旧观察者仍在监听订单。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=== 我什至尝试过 handle ,但没有用:
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 = []
}
}
}
最佳答案
我想我可能已经修复了它?所以这是因为我实际上是在该引用的子节点上进行观察,因此删除父节点的所有观察者不会执行任何操作,因为您必须在正在观察的特定节点上删除它。
let pendingOrdersReference = FIRDatabase
.database()
.reference(withPath: "\(ORDERS_PATH)/\(lId)")
.child(dateKeyToday()) // <---- added this thing
这是我的最终解决方案,它似乎有效:
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 = []
}
}
关于swift - Firebase + swift : removeAllObservers not working?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/40772101/