“无法将 '(String) -> Bool' 类型的值转换为预期参数”

Posted 2023-03-12

【中文标题】“无法将 \'(String) -> Bool\' 类型的值转换为预期参数”

【英文标题】："Cannot convert value of type '(String) -> Bool' to expected argument "“无法将 '(String) -> Bool' 类型的值转换为预期参数”

【发布时间】：2017-03-18 20:40:40

【问题描述】：

我在使用 IndexPath.row 数据为我的 TableView 实现 SearchBar 时遇到了一些问题

我不知道如何处理此错误消息：

无法将 (String) -> Bool 类型的值转换为预期的参数类型 (postStruct) -> Bool

我在func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) 中收到此错误消息

这是我的代码

import UIKit
import Firebase
import FirebaseDatabase

    struct postStruct 
        let username : String!
        let school : String!
    

class TableViewProfileController: UITableViewController, UISearchBarDelegate 


    @IBOutlet weak var searchBar: UISearchBar!

    var posts:[postStruct] = []

    override func viewDidLoad() 
        super.viewDidLoad()

        self.title = "Find friends"
        searchBar.delegate = self
        tableView.dataSource = self


        //Hide backButton in Navigationbar
        self.navigationItem.setHidesBackButton(true, animated: false)

        // SearchController
        searchBar.sizeToFit()
        searchBar.searchBarStyle = .minimal
        searchBar.placeholder = "Search here..."
        searchBar.setShowsCancelButton(false, animated: true)
        searchBar.keyboardAppearance = .default
        searchBar.tintColor = UIColor(red: 38.0/255.0, green: 68.0/255.0, blue: 102.0/255.0, alpha:  1.0)
        self.definesPresentationContext = true
        self.tableView.reloadData()

    // TableView Cell Content
    let databaseRef = FIRDatabase.database().reference()

        databaseRef.child("users").queryOrderedByKey().observe(.childAdded, with: 
            snapshot in
            let snapshotValue = snapshot.value as? NSDictionary
            let username = snapshotValue!["Username"] as! String
            let school = snapshotValue!["School"] as! String

            self.posts.insert(postStruct(username: username, school: school) , at: 0)
            self.tableView.reloadData()
        )
    

        func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) 
        posts = searchText.isEmpty ? posts : posts.filter((dataString: String) -> Bool in
            return dataString.range(of: searchText, options: .caseInsensitive) != nil
        )

        tableView.reloadData()
    

    func searchBarTextDidBeginEditing(_ searchBar: UISearchBar) 
        self.searchBar.showsCancelButton = true
    

    func searchBarCancelButtonClicked(_ searchBar: UISearchBar) 
        searchBar.showsCancelButton = false
        searchBar.text = ""
        searchBar.resignFirstResponder()
    

    override func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat 
        return 2.0
    

    override func didReceiveMemoryWarning() 
        super.didReceiveMemoryWarning()
    

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

        return self.posts.count
    

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell 

        let cell = tableView.dequeueReusableCell(withIdentifier: "Cell")

        let label1 = cell?.viewWithTag(1) as! UILabel
        label1.text = posts[indexPath.row].username
        label1.font = UIFont(name: "Arial Rounded MT Bold", size: 16)
        label1.textColor = UIColor.black

        let label2 = cell?.viewWithTag(2) as! UILabel
        label2.text = posts[indexPath.row].school
        label2.font = UIFont(name: "Arial", size: 11)
        label2.textColor = UIColor(red: 102.0/255.0, green: 102.0/255.0, blue: 102.0/255.0, alpha:  1.0)


        cell?.imageView?.image = UIImage(named: "Userlogo")

        return cell!
        


    //Preparing Segue to show username in FindUserViewController
    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) 

        performSegue(withIdentifier: "findSegue", sender: self.posts[indexPath.row].username)
    

    //Segue to show username in FindUserViewController
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) 

        if segue.identifier! == "findSegue" 
        let guest = segue.destination as! FindUserViewController
        guest.pickedUser = sender as! String

        let backItem = UIBarButtonItem()
        backItem.title = "Back"
        navigationItem.backBarButtonItem = backItem

        
    

【参考方案1】：

您将filter 函数应用于postStruct 数组，因此语法至少为

posts.filter( (post: postStruct) -> Bool in ... )

或更短

posts.filter  post in ... 

你可以搜索

posts = searchText.isEmpty ? posts : posts.filter  post in
        return post.username.range(of: searchText, options: .caseInsensitive) != nil

旁注：

请，请不要 - 永远不要 - 在结构中声明隐式未包装的可选成员。

要么它们确实是可选的，然后将它们声明为String?，要么它们是非可选的，然后去掉感叹号。

【讨论】：

谢谢.. 错误消失了。现在我只需要弄清楚为什么不进行任何搜索