如果我想搜索用户喜欢的书，其标题是《哈利·波特》，请使用UISearchController，以进行快照：
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
...
})
}
如果我想搜索某个位置的用户，请使用GeoFire执行以下操作：
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
...
})
如何使用UISearchController组合这两个查询，以便可以在距离我5公斤的范围内获得所有拥有“哈利·波特”最喜欢的书名的用户的快照？
该人说to this link只是在GFQueryResultBlock中添加了第三个参数作为快照，但没有说明该快照如何到达另一个节点以提取数据。
我的数据库（显示1位用户，但附近可能有20位用户出现在搜索结果中）：
-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
到目前为止我尝试过的。基本上，我首先检查了距离设备最近的所有用户，然后将它们放在名为usersInRadius的数组中。之后，我检查了对在搜索栏中输入的文本的查询，并将这些结果添加到名为favoriteBooks的数组中。我将它们都投射为Set，并尝试使用Set的.intersection()函数比较它们中包含的项目，但未得到警告
“路口”调用结果未使用
然后，我将该函数的最终结果放入名为finalResults的数组中，以显示在collectionView中。
搜索有效，我从finalResults数组中获得了哈利波特书籍，但对我附近的用户的过滤并没有过滤掉每本。我认为问题发生在步骤19：
favoriteBooksAsSet.intersection(usersInRadiusAsSet) // I get the warning message above
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)
}
}
}
答案 0 :(得分：0)
我得到了answer from this SO answer
问题出在我在步骤18和19上分离集合的过程中：
// 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))
}
更正的解决方案是使用SO答案中的内容并将两个数组组合为Sets，然后将相交方法得到的任何结果都使用该结果放入步骤20中：
// 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))