使用GeoFire检查附近是否没有位置

Question

我正在尝试使用GeoFire搜索附近的注册位置，如果指定的半径范围内没有默认值，则返回默认值。 我的问题是，当GeoFire在附近找不到任何东西时，它绝对不会返回任何东西。 有其他方法可以做到这一点吗？

    let geoFire = GeoFire(firebaseRef: DataService().LOC_REF)
    let myLoc = CLLocation(latitude: 10.500000, longitude: -100.916664)
    let circleQuery = geoFire.queryAtLocation(myLoc, withRadius: 100.0)
    circleQuery.observeEventType(GFEventType.KeyEntered, withBlock: {
        (key: String!, location: CLLocation!) in
        self.allKeys[key]=location
        print(self.allKeys.count) //NOT GETTING HERE
        print(key)
        //from here i'd like to use the key for a different query, or determine if there are no keys nearby
            }
        })
    })

提前致谢

Answer 1

这是您可以使用这两个功能构建键列表的方法，并在列表创建完成后进行侦听。

func fetchLocations() {
    keys = [String]()

    let geoFire = GeoFire(firebaseRef: DataService().LOC_REF)
    let myLoc = CLLocation(latitude: 10.500000, longitude: -100.916664)
    let circleQuery = geoFire.queryAtLocation(myLoc, withRadius: 100.0)

    // Populate list of keys
    circleQuery.observeEventType(.KeyEntered, withBlock: { (key: String!, location: CLLocation!) in
        print("Key '\(key)' entered the search area and is at location '\(location)'")
        keys.append(key)
    })

    // Do something with list of keys.
    circleQuery.observeReadyWithBlock({
        print("All initial data has been loaded and events have been fired!")
        if keys.count > 0 {
            // Do something with stored fetched keys here.
            // I usually retrieve more information for a location from firebase here before populating my table/collectionviews.  
        }

    })
}

Answer 2

您将要等待查询报告完成。 从GeoFire文档中 ：

有时您想知道何时从服务器加载了所有初始密钥的数据，并且这些密钥的相应事件已被触发。 例如，您可能要在数据完全加载后隐藏加载动画。 GFQuery提供了一种侦听这些就绪事件的方法：

query.observeReadyWithBlock({
  println("All initial data has been loaded and events have been fired!")
})