ios - Swift iOS Firebase - 如何结合 queryOrdered(byChild) 和 GeoFire observe(.keyEntered) 来同时获取快照和位置结果？

Question

使用UISearchController如果我想搜索用户最喜欢的书名是哈利波特的书，我会执行以下操作来获取它的快照：

func updateSearchResults(for searchController: UISearchController) {

    // the searchText the user entered is Harry Potter
    guard let searchText = searchController.searchBar.text?.lowercased() else { return }

    let favoriteBooksRef = Database.database().reference().child("searchFavoriteBooks").queryOrdered(byChild: "titleLowercased").queryStarting(atValue: searchText).queryEnding(atValue: searchText+"\u{f8ff}")

    favoriteBooksRef.observeSingleEvent(of: .value, with: { (snapshot) in
        ...
    })
}

如果我想在某个位置搜索用户，我会执行以下操作GeoFire：

let geofireRef = Database.database().reference().child("users_locations")
let geoFire = GeoFire(firebaseRef: geofireRef)
let center = CLLocation(latitude: myLat, longitude: myLon)

let circleQuery = geoFire.query(at: center, withRadius: 5)

var queryHandler = circleQuery.observe(.keyEntered, with: { (key: String!, location: CLLocation!) in
       ...
})

我如何使用 UISearchController 来组合这两个查询，以便我可以在距离我所在的位置 5 公里范围内获得所有用户的快照，其中包含最喜欢的哈利波特书名？

根据此链接，该人说只需在其中添加第三个参数作为快照，GFQueryResultBlock但它没有解释该快照如何到达不同的节点以从中提取数据。

我的数据库（它显示 1 个用户，但附近可能有 20 个用户将出现在搜索结果中）：

-root
   |
   @--users
   |    |
   |    @---uid789
   |          |
   |          |--username: "avidBookReader"
   |          |--lat: 34.111
   |          |--lon: -34.222
   |          @---postId001
   |                  |
   |                  |--title: "Harry Potter"
   |
   @--users_location
   |    |
   |    @---uid789
   |          |
   |          |--g: xyz234
   |          @--l:      
   |              |--0: 34.111
   |              |--1: -34.222
   |
   @--searchFavoriteBooks
        |
        @---postId001
               |
               |--uid: "uid789"
               |--titleLowercased: "harry potter"
               |--lat: 34.111
               |--lon: -34.222

到目前为止我尝试了什么。我基本上首先检查了所有最接近设备的用户，然后将它们放在一个名为usersInRadius. 之后，我检查了对在搜索栏中输入的文本运行查询并将这些结果添加到名为favoriteBooks. 我将它们都投射为 aSet并且尝试使用 Set 的.intersection()函数比较其中包含的项目但未成功，我收到警告

调用'intersection'的结果未使用

然后，我将该函数的最终结果放入一个命名finalResults为在 collectionView 中显示的数组中。

搜索有效，我从数组中获得了哈利波特书籍，finalResults但对我附近的用户的过滤并没有过滤掉每一本。我认为问题发生在第 19 步：

favoriteBooksAsSet.intersection(usersInRadiusAsSet) // I get the warning message above

它过滤不正确。这是下面的代码。

let radius: Double = 5.0
let usersInRadius = [SearchModels] // an arr of all the users in the vicinity 
let favoriteBooks = [SearchModels] // an arr of all the results that contain the searchText
let finalResults = [SearchModels] // the final array that will display the results of the users in the vicinity with the search text by comparing the 2 above arrays as Sets

// 1. user enters text into the searchBar
func updateSearchResults(for searchController: UISearchController) {

    // 2. the text is Harry Potter
    guard let searchText = searchController.searchBar.text?.lowercased() else { return }

    // 3. look for all the users in the devices proximity
    getAlltheUsersInTheChosenRadius(radius: radius, searchText: searchText)
} 

func getAlltheUsersInTheChosenRadius(radius: Double, searchText: String) {

    // 4. check for location authorization
    if (CLLocationManager.authorizationStatus() == .authorizedWhenInUse ||
        CLLocationManager.authorizationStatus() ==  .authorizedAlways) {

        currentLocation = locationManager.location

        // 5. get the device's lat and lon
        let myLat = currentLocation.coordinate.latitude
        let myLon = currentLocation.coordinate.longitude

        // 6. use them to create a CLLocation
        let center = CLLocation(latitude: myLat, longitude: myLon)

        // 7. create the geoFire node to search on
        let geofireRef = Database.database().reference().child("users_location")
        let geoFire = GeoFire(firebaseRef: geofireRef)

        // 7. center in a 5 meter radius
        let circleQuery = geoFire.query(at: center, withRadius: radius)

        // 8. get the .keyEntered info
        let queryHandler = circleQuery.observe(.keyEntered, with: {
            (key: String!, location: CLLocation!) in

            // 9. create a SearchModel object and set the key to the userId's key and the location to the location
            let searchModel = SearchModel()
            searchModel.userId = key
            searchModel.location = location

            // 10. append these objects to an array of all the users who are in the vicinity      
            self.usersInRadius.append(searchModel)
        })

        // 11. geoFire is done now query the searchText
        circleQuery.observeReady({

            self.queryTheSearchFavoriteBooksNode(searchText: searchText)
        })
    }
}

func queryTheSearchFavoriteBooksNode(searchText: searchText) {

    // 12. set the ref for the searchFavoriteBooks to search on
    let favoriteBooksRef = Database.database().reference().child("searchFavoriteBooks").queryOrdered(byChild: "titleLowercased").queryStarting(atValue: searchText).queryEnding(atValue: searchText+"\u{f8ff}")

    favoriteBooksRef.observeSingleEvent(of: .value, with: { (snapshot) in

        guard let dictionaries = snapshot.value as? [String: Any] else {
            self.finalResults.removeAll()
            self.collectionView.reloadData()
            return
        }

        // 14. grab all the key/values pairs that have a value named "harry potter"
        dictionaries.forEach({ (key, value) in

            guard let dict = value as? [String: Any] else { return }

            // 15. init a SearchModel with the values from the dict
            let searchModel = SearchModel(dict: dict)

            // 16. check if the result is in the favoriteBooks array
            let isContained = self.favoriteBooks.contains(where: { (post) -> Bool in
                return searchModel.userId == post.userId
            })

            // 17. if it's not in the favoriteBooks array the append it to it
            if !isContained {
                self.favoriteBooks.append(searchModel)

                if self.favoriteBooks.count > 1 {

                    // 18. if there is more then 1 item in the favoriteBooks then cast it as a Set and also cast the userInRadius from step 10 as a Set
                    let favoriteBooksAsSet = Set(self.favoriteBooks)
                    let usersInRadiusAsSet = Set(self.usersInRadius)

                    // 19. compare the items in both sets and remove what I don't want. This ISN'T working
                   favoriteBooksAsSet.intersection(usersInRadiusAsSet)

                    // 20. append the results from the favoriteBooksAsSet in step 19 to the final finalResults which should display the UISearchController's results
                    self.finalResults.append(contentsOf: Array(favoriteBooksAsSet))
                }
                self.collectionView?.reloadData()
            }
        })
    })
}

// this is the SearchModel
class SearchModel: : Equatable, Hashable {

    var hashValue: Int {
        guard let uid = userId, let loc = location else {
            return Int(arc4random())
        }
        return uid.djb2hash ^ loc.hashValue
    }

    var postId: String?
    var title: String?
    var userId: String?
    var location: CLLocation?
    var lat: CLLocationDegrees?
    var lon: CLLocationDegrees?

    convenience init(dict: [String: Any]) {
        self.init()

        postId = dict["postId"] as? String
        title = dict["title"] as? String
        userId = dict["userId"] as? String
        location = dict["location"] as? CLLocation
        lat = dict["lat"] as? CLLocationDegrees
        lon = dict["lon"] as? CLLocationDegrees
    }

    static func == (lhs: SearchModel, rhs: SearchModel) -> Bool {
        return lhs.userId == rhs.userId
    }
}

// String extension for the hash value in the SearchModel
extension String {
    var djb2hash: Int {
        let unicodeScalars = self.unicodeScalars.map { $0.value }
        return unicodeScalars.reduce(5381) {
            ($0 << 5) &+ $0 &+ Int($1)
        }
    }
}

标签： iosswiftfirebaseuisearchcontrollergeofire

Answer 1

我从这个 SO answer 得到了答案

问题在于我在第 18 步和第 19 步中对集合进行了分离：

// 18. if there is more then 1 item in the favoriteBooks then cast it as a Set and also cast the userInRadius from step 10 as a Set
let favoriteBooksAsSet = Set(self.favoriteBooks)
let usersInRadiusAsSet = Set(self.usersInRadius)

// 19. compare the items in both sets and remove what I don't want. This ISN'T working
favoriteBooksAsSet.intersection(usersInRadiusAsSet)

// 20. append the results from the favoriteBooksAsSet in step 19 to the final finalResults which should display the UISearchController's results
self.finalResults.append(contentsOf: Array(favoriteBooksAsSet))
            }

更正解决方案是使用 SO 答案中的内容并将两个数组组合为 Set，然后无论交集方法的结果如何，都将其放入步骤 20：

// steps 18 and 19 combined
let tempSet = Set(self.favoriteBooks).intersection(Set(self.usersInRadius))

// 20. append the results from the tempSet in step 18 and 19 to the final finalResults which should display the UISearchController's results
self.finalResults.append(contentsOf: Array(tempSet))