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使用removeObserver(在Swift 3中使用withHandle,在viewDidDisappear上不删除Observer

var query = FIRDatabaseQuery()

var postRef: FIRDatabaseReference!
var postRefHandle: FIRDatabaseHandle?

override func viewDidLoad() {
    super.viewDidLoad()

    postRef = baseRef.child("Posts")
}

override func viewDidDisappear(_ animated: Bool) {
    super.viewDidDisappear(animated)

    if postRefHandle != nil {
        //try 1:
        //postRef.removeObserver(withHandle: postRefHandle!)

        //try 2:
        //postRef.queryOrdered(byChild: "sortTimestamp").removeObserver(withHandle: postRefHandle!)

        //try 3: 
        //query.removeObserver(withHandle: postRefHandle!)
    }
    //try 4:
    //postRef.removeAllObservers() //works
}

func getPosts()
{
    var count = 20 

    query = postRef.queryOrdered(byChild: "sortTimestamp")

    postRefHandle = query.queryLimited(toFirst: UInt(count)).observe(.childAdded //etc.
}

所以我尝试了viewDidDisappear中的三个方法,但是没有删除观察者.尝试3来自Firebase的 query.removeObserver(withHandle:postRefHandle!),如何返回句柄以便我可以调用removeObserver？作者:frank-van-puffelen

唯一有效的是try 4中概述的那个.我无法用removeObserver删除Observer的任何原因(withHandle？(try 1 - 3)

另外"query.queryLimited(toFirst:UInt(count)).观察(.childAdded"没有从Firebase获取最新数据.我认为观察总是得到更新的数据,而不是observeSingleEvent.为什么不是去做？ …

这是 Swift、Firebase 和 Geofire 的问题。

我想知道如何在 Swift 中删除以下观察者的 GeoFire 句柄。

locationsEnd!.query(at: location, withRadius: 16.0).observe(GFEventType.init(rawValue: 0)!, with: {(key, location) in

以下工作正常（在 viewDidDisappear 中）：

locationsEnd?.firebaseRef.removeAllObservers()

然而，对于句柄来说，它不会：

var locationHandle: UInt = 0

override func viewDidDisappear(_ animated: Bool) {
    super.viewDidDisappear(animated)

    //following does not work:
    locationsEnd?.firebaseRef.removeObserver(withHandle: locationHandle)
}

func aroundMe(_ location: CLLocation){

        locationHandle = locationsEnd!.query(at: location, withRadius: 16.0).observe(GFEventType.init(rawValue: 0)!, with: {(key, location) in

            //etc
        })
}

我尝试了如下locationHandle，但没有成功：

var locationHandle = FirebaseHandle()
var locationHandle: FirebaseHandle = 0
var locationHandle: UInt!
var locationHandle: UInt = 0
var …