无法识别Swift 5中的线程1:致命错误:超出范围的索引

Question

我正在构建一个IOS字典应用程序。我正在创建一个带有viewTable的searchBar，以搜索单词并显示正在键入的搜索结果。例如，如果用户输入"app"，viewTable应该显示"app，apple，apply“等。下面是我所拥有的，请帮助，谢谢。

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var searchBar: UISearchBar!
    @IBOutlet weak var tableView: UITableView!

    var wordSearch = [String]()
    var searching = false
    var wordArray: [String] = []

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.

        let url = Bundle.main.url(forResource: "words_alpha", withExtension: "txt")! // file URL for file "words_alpha.txt"
               do {
                   let string = try String(contentsOf: url, encoding: .utf8)
                   wordArray = string.components(separatedBy: CharacterSet.newlines)
               } catch {
                   print(error)
               }
    }
}

extension ViewController: UITableViewDataSource, UITableViewDelegate {
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        if searching {
            return wordArray.count
        } else {
            return wordArray.count
        }

    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "cell");cell?.textLabel?.text = wordArray[indexPath.row]
        if searching {
            cell?.textLabel?.text = wordSearch[indexPath.row] //Thread 1: Fatal error: Index out of range
        } else {
            cell?.textLabel?.text = wordSearch[indexPath.row]
        }
            return cell!
        }
    }

extension ViewController: UISearchBarDelegate {
    func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {
        wordSearch = wordArray.filter({$0.prefix(searchText.count) == searchText;})
        searching = true
        tableView.reloadData()
   }
}

Answer 1

首先，如果搜索字段为空，则必须处理该案件。

还有一种更高效、更可靠的语法来过滤数组：range(of可以同时过滤不区分大小写和从字符串开始(anchored)开始。

extension ViewController: UISearchBarDelegate {
    func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {
        if searchText.isEmpty {
            searching = false
            wordSearch.removeAll()
        } else {
            wordSearch = wordArray.filter{ $0.range(of: searchText, options: [.caseInsensitive, .anchored]) != nil }
            searching = true
        }
        tableView.reloadData()
   }
}

要修复错误，您必须从wordSearch或wordArray获取数据，这取决于searching。将numberOfRowsInSection和cellForRowAt替换为

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return searching ? wordSearch.count : wordArray.count
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for indexPath)
    let word = searching ? wordSearch[indexPath.row] : wordArray[indexPath.row]
    cell.textLabel?.text = word
    return cell
}

Answer 2

设置数组的计数。

if searching {
  return wordArray.count

并在这里索引其他的一个

if searching {
   cell?.textLabel?.text = wordSearch[indexPath.row] //Thread 1: Fatal error: Index out of range

所以用吧

if searching {
  return wordSearch.count
} else {
  return wordArray.count
}

随同

if searching {
     cell?.textLabel?.text = wordSearch[indexPath.row] //Thread 1: Fatal error: Index out of range
} else {
    cell?.textLabel?.text = wordArray[indexPath.row]
}

Answer 3

The above answer is right . 

Adding to it. The search filtering g method seems to be wrong

func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {
        **wordSearch = wordArray.filter({$0.prefix(searchText.count) == searchText;})**
        searching = true
        tableView.reloadData()
   }

Instead use **wordArray.filter({$0.contains(searchText)})**

And on clearing the search bar . Reset searching = false and empty the wordSearch array.
Check whether you need to set the searchBar.delegate = self in viewDidLoad.