问题
I'm trying to accomplish searching for other users only when the user has typed at least 2 words, and only then begin the search in the database (because I don't want to scan the entire database for the users). I had some problems with 2 letter search, but I think I got the code (thanks to user Jay).
However when I run it in the simulator, the console prints name, but nothing shows up in the tableview? (its empty).
Do you know what I have done wrong?
This is my code:
class FollowUsersTableViewController: UIViewController {
@IBOutlet var tableView: UITableView!
private var viewIsHiddenObserver: NSKeyValueObservation?
let searchController = UISearchController(searchResultsController: nil)
var usersArray = [UserModel]()
var filteredUsers = [UserModel]()
var loggedInUser: User?
//
var databaseRef = Database.database().reference()
//usikker på den koden over
override func viewDidLoad() {
super.viewDidLoad()
searchController.searchBar.delegate = self
//large title
self.title = "Discover"
if #available(iOS 11.0, *) {
self.navigationController?.navigationBar.prefersLargeTitles = true
} else {
// Fallback on earlier versions
}
self.tableView?.delegate = self
self.tableView?.dataSource = self
searchController.searchResultsUpdater = self
searchController.dimsBackgroundDuringPresentation = false
self.searchController.delegate = self;
definesPresentationContext = true
tableView.tableHeaderView = searchController.searchBar
}
func searchUsers(text: String) {
if text.count >= 2 {
self.usersArray = [] //clear the array each time
let endingText = text + "\u{f8ff}"
databaseRef.child("profile").queryOrdered(byChild: "username")
.queryStarting(atValue: text)
.queryEnding(atValue: endingText)
.observeSingleEvent(of: .value, with: { snapshot in
for child in snapshot.children {
let childSnap = child as! DataSnapshot
print(childSnap)
let userObj = Mapper<UserModel>().map(JSONObject: childSnap.value!)
userObj?.uid = childSnap.key
if childSnap.key != self.loggedInUser?.uid { //ignore this user
self.usersArray.append(userObj!)
}
}
self.tableView.reloadData()
})
}
} //may need an else statement here to clear the array when there is no text
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
let dest = segue.destination as! UserProfileViewController
let obj = sender as! UserModel
let dict = ["uid": obj.uid!, "username": obj.username!, "photoURL": obj.photoURL, "bio": obj.bio]
dest.selectedUser = dict as [String : Any]
}
}
// MARK: - tableview methods
extension FollowUsersTableViewController: UITableViewDataSource, UITableViewDelegate {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return searchController.searchBar.text!.count >= 2 ? filteredUsers.count : 0
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! FollowTableViewCell
let user = filteredUsers[indexPath.row]
cell.title?.text = user.username
if let url = URL(string: user.photoURL ?? "") {
cell.userImage?.sd_setImage(with: url, placeholderImage: #imageLiteral(resourceName: "user_male"), options: .progressiveDownload, completed: nil)
cell.userImage.sd_setIndicatorStyle(.gray)
cell.userImage.sd_showActivityIndicatorView()
}
return cell
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 50
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
self.performSegue(withIdentifier: "user", sender: self.filteredUsers[indexPath.row])
}
}
// MARK: - search methods
extension FollowUsersTableViewController:UISearchResultsUpdating, UISearchControllerDelegate, UISearchBarDelegate {
func updateSearchResults(for searchController: UISearchController) {
searchController.searchResultsController?.view.isHidden = false
self.searchUsers(text: self.searchController.searchBar.text!)
filterContent(searchText: self.searchController.searchBar.text!)
self.tableView.reloadData()
}
func filterContent(searchText:String){
if searchText.count >= 2{
self.filteredUsers = self.usersArray.filter{ user in
return(user.username!.lowercased().contains(searchText.lowercased()))
}
}
}
}
回答1:
You have 2 arrays usersArray and filteredUsers
if childSnap.key != self.loggedInUser?.uid { //ignore this user
self.usersArray.append(userObj!)
}
...
self.tableView.reloadData()
so the the above reload has no effect as you always use
let user = filteredUsers[indexPath.row]
in cellForRowAt , in such cases you should have a var like
var isSearching = false
and alter it when you search then in all delegate & dataSource methods
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return isSearching ? filteredUsers.count : usersArray.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! FollowTableViewCell
let user = isSearching ? filteredUsers[indexPath.row] : usersArray[indexPath.row]
.....
}
func searchBarTextDidBeginEditing(_ searchBar: UISearchBar) {
isSearching = true
}
func searchBarTextDidEndEditing(_ searchBar: UISearchBar) {
isSearching = false
}
func searchBarCancelButtonClicked(_ searchBar: UISearchBar) {
isSearching = false
}
func searchBarSearchButtonClicked(_ searchBar: UISearchBar) {
isSearching = false
}
func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {
filteredUsers = usersArray.filter { /* do filter */ }
if(filteredUsers.count == 0){
isSearching = false
} else {
isSearching = true
}
self.tableView.reloadData()
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
self.performSegue(withIdentifier: "user", sender: isSearching ? self.filteredUsers[indexPath.row] : self.usersArray[indexPath.row])
}
回答2:
This code is very close, and as the other answer points out you've got two arrays.
But let's really simplify the issue: You only need one array since you are filtering Firebase, not the array.
In other words when a user types into the searchField, you're querying Firebase for results and putting them into an array. That's the same array you should be using as the dataSource for your tableView.
As your code sits, you're filtering Firebase and then filtering those results again which isn't needed.
So at a high level supposed we have four users in our database
Larry
Moe
Monroe
Curly
the user types 'Mo' into the search field which causes your Fire query to execute. It will return two results:
Mo
Monroe
which then gets populated into an array - we'll call it userResultsArray.
then
tableView.reloadData()
which then calls the tableView delegate methods
func tableView(_ tableView: UITableView, numberOfRowsInSection
return userResultsArray.count
and
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath)
get the user from userResultsArray
return the user name
As shown, you only need the single array to store the queried (filtered) results from Firebase.
来源：https://stackoverflow.com/questions/54111912/why-dosent-my-tableview-show-search-results