swift - '不能在集合中使用/包含运算符'

Question

单击搜索栏时出现此错误:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Can't use in/contains operator with collection Assignment_4.SearchResult(studentID: "1060", lastName: "Squarepants", firstName: "Spongebob", major: "Krusty Krab Chef", year: "Junior", gpa: "4.0") (not a collection)'

获取此行的错误。

let array = (results as NSArray).filtered(using: searchPredicate)

这是完整的代码。我不知道出了什么问题。谢谢!!

var results = [SearchResult]()
var indexN = 0
var addStudent = false
var searchController: UISearchController!

var filteredTableData = [String]()
var resultSearchController = UISearchController()


@IBAction func AddStudentButton(_ sender: Any) {
    addStudent=true
    performSegue(withIdentifier: "detailSegue", sender: self)
}

@IBAction func refreshButton(_ sender: Any) {
    refreshTable()
}

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    listTableView.delegate = self
    listTableView.dataSource = self

    listTableView.reloadData()

    jsonParser()

    self.resultSearchController = ({

        let controller = UISearchController(searchResultsController: nil)

        controller.searchResultsUpdater = self

        controller.dimsBackgroundDuringPresentation = true

        controller.searchBar.sizeToFit()



        self.listTableView.tableHeaderView = controller.searchBar



        return controller

    })()
    self.listTableView.reloadData()


}

/*
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return 1
}
*/

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

    if (self.resultSearchController.isActive) {

        return self.filteredTableData.count

    }

    else {

        return self.results.count

    }

    // return self.results.count
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell:UITableViewCell = UITableViewCell(style:UITableViewCellStyle.subtitle, reuseIdentifier: "cell")
    //cell.textLabel!.text = self.results[indexPath.row].firstName + " " + results[indexPath.row].lastName
    //return cell

   // let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)



    if (self.resultSearchController.isActive) {

        cell.textLabel?.text = filteredTableData[indexPath.row]



        return cell

    }

    else {

        cell.textLabel?.text = self.results[indexPath.row].firstName + " " + results[indexPath.row].lastName
        return cell

    }

}

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    indexN = indexPath.row
    addStudent=false
    performSegue(withIdentifier: "detailSegue", sender: self)
}

func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
    return true
}

func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
    if (editingStyle == UITableViewCellEditingStyle.delete) {
        // handle delete (by removing the data from your array and updating the tableview)
        Delete(studentID: self.results[indexN].studentID)
        refreshTable()
    }
}

func numberOfSections(in tableView: UITableView) -> Int {

    return 1

}




override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

func jsonParser() {
    let urlPath = "http://csmadison.dhcp.bsu.edu/~vjtanksale/cs320/selectstudents.php"
    guard let endpoint = URL(string: urlPath) else {
        print("Error creating endpoint")
        return
    }
    let request = URLRequest(url: endpoint)
    URLSession.shared.dataTask(with: request) { (data, response, error) in
        do {
            guard let data = data else {
                return
            }
            guard let json = try JSONSerialization.jsonObject(with: data, options: []) as? [[String:AnyObject]] else {
                print("No idea")
                return
            }

            for result in json {
                if let student = SearchResult(json: result) {
                    self.results.append(student)
                }
            }
            self.grabData()
        } catch let error as NSError {
            print(error.debugDescription)
        }
        }.resume()
}

func grabData() {
    DispatchQueue.main.async {
        self.listTableView.reloadData()
    }
}

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if(addStudent==false){
        let newVC: DetailViewController = segue.destination as! DetailViewController
        newVC.result = results[indexN]
        newVC._label1 = results[indexN].studentID
        newVC._label2 = results[indexN].lastName
        newVC._label3 = results[indexN].firstName
        newVC._label4 = results[indexN].major
        newVC._label5 = results[indexN].year
        newVC._label6 = results[indexN].gpa
    }
    else if(addStudent==true){
        let newVC: DetailViewController = segue.destination as! DetailViewController
        newVC.addStudent=true
    }

}

func Delete(studentID: String) {
    let request = NSMutableURLRequest(url: NSURL(string: "http://csmadison.dhcp.bsu.edu/~vjtanksale/cs320/deletestudents.php")! as URL)
    request.httpMethod = "POST"
    let postString = "StudentId="+studentID
    request.httpBody = postString.data(using: String.Encoding.utf8)

    let task = URLSession.shared.dataTask(with: request as URLRequest) {
        data, response, error in

        if error != nil {
            print("error=\(error)")
            return
        }

        print("response = \(response)")

        let responseString = NSString(data: data!, encoding: String.Encoding.utf8.rawValue)
        print("responseString = \(responseString)")
    }
    task.resume()
}

func refreshTable(){
    results.removeAll()
    self.listTableView.reloadData()
    jsonParser()
    self.listTableView.reloadData()
}

func updateSearchResults(for searchController: UISearchController)

{

    filteredTableData.removeAll(keepingCapacity: false)



    let searchPredicate = NSPredicate(format: "SELF CONTAINS[c] %@", searchController.searchBar.text!)

    let array = (results as NSArray).filtered(using: searchPredicate)

    filteredTableData = array as! [String]



    self.listTableView.reloadData()

}

Answer 1

您收到此错误是因为您尝试在 SearchResult 对象上使用 CONTAINS 谓词，这些对象不是具有定义的 概念的集合包含。这个错误发生在运行时，因为 NSPredicate 在运行时解析和处理它的字符串。为此，最好使用本地 swift 工具:

let searchTerm = searchController.searchBar.text!

let array = results.filter { result in
    return result.studentID.contains(searchTerm) ||
           result.something.contains(searchTerm) // and so on...
}