如何在 Swift 中添加搜索栏？

Question

I'm trying to add a search bar in this pokedex. I want to add a search bar which filters out data when typed. The search bar doesn't filter out data when typed. I'm new to programming so really not sure where I'm wrong. Any help would be much appreciated. Here's my code

import UIKit

class PokemonListViewController: UITableViewController, UISearchBarDelegate {
    
    @IBOutlet var searchBar: UISearchBar!
    var pokemon: [PokemonListResult] = []
    var filteredData: [PokemonListResult] = []
    var pokeSearch = false
    
    func capitalize(text: String) -> String {
        return text.prefix(1).uppercased() + text.dropFirst()
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        searchBar.delegate = self
        
        guard let url = URL(string: "https://pokeapi.co/api/v2/pokemon?limit=151") else {
            return
        }
        
        URLSession.shared.dataTask(with: url) { (data, response, error) in
            guard let data = data else {
                return
            }
            
            do {
                let entries = try JSONDecoder().decode(PokemonListResults.self, from: data)
                self.pokemon = entries.results
                self.filteredData = self.pokemon
                DispatchQueue.main.async {
                    self.tableView.reloadData()
                }
            }
            catch let error {
                print(error)
            }
        }.resume()
    }
    
    override func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }
    
    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        if pokeSearch {
            return filteredData.count
        } else {
            return pokemon.count
        }
    }
    
    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "PokemonCell", for: indexPath)
        if pokeSearch {
            cell.textLabel?.text = capitalize(text: filteredData[indexPath.row].name)
        } else {
            cell.textLabel?.text = capitalize(text: pokemon[indexPath.row].name)
        }
        return cell
    }
    
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "ShowPokemonSegue",
                let destination = segue.destination as? PokemonViewController,
                let index = tableView.indexPathForSelectedRow?.row {
            destination.url = pokemon[index].url
        }
    func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {
        if searchBar.text == " " || searchBar.text == nil {
            pokeSearch = false
            tableView.reloadData()
        } else {
            
            //let lower = searchBar.text!.lowercased()
            
            //filteredData = pokemon.filter({$0.name.range(of: lower) != nil})
            filteredData = pokemon.filter({pokemon -> Bool in
                pokemon.name.contains(searchText)
            })
            pokeSearch = true
                       
            tableView.reloadData()
            
        }
    }
}

}

PokemonViewController

import UIKit

class PokemonViewController: UIViewController { var url: String!

@IBOutlet var nameLabel: UILabel!
@IBOutlet var numberLabel: UILabel!
@IBOutlet var type1Label: UILabel!
@IBOutlet var type2Label: UILabel!

func capitalize(text: String) -> String {
    return text.prefix(1).uppercased() + text.dropFirst()
}

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    nameLabel.text = ""
    numberLabel.text = ""
    type1Label.text = ""
    type2Label.text = ""

    loadPokemon()
}

func loadPokemon() {
    URLSession.shared.dataTask(with: URL(string: url)!) { (data, response, error) in
        guard let data = data else {
            return
        }

        do {
            let result = try JSONDecoder().decode(PokemonResult.self, from: data)
            DispatchQueue.main.async {
                self.navigationItem.title = self.capitalize(text: result.name)
                self.nameLabel.text = self.capitalize(text: result.name)
                self.numberLabel.text = String(format: "#%03d", result.id)

                for typeEntry in result.types {
                    if typeEntry.slot == 1 {
                        self.type1Label.text = typeEntry.type.name
                    }
                    else if typeEntry.slot == 2 {
                        self.type2Label.text = typeEntry.type.name
                    }
                }
            }
        }
        catch let error {
            print(error)
        }
    }.resume()
}

}

Pokemon

import Foundation

struct PokemonListResults: Codable {
    let results: [PokemonListResult]
}

struct PokemonListResult: Codable {
    let name: String
    let url: String
}

struct PokemonResult: Codable {
    let id: Int
    let name: String
    let types: [PokemonTypeEntry]
}

struct PokemonTypeEntry: Codable {
    let slot: Int
    let type: PokemonType
}

struct PokemonType: Codable {
    let name: String
}

Answer 1

The logic is fine, but you accidentally put the textDidChange delegate method inside the prepare method, so that it does not get called:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "ShowPokemonSegue",
                let destination = segue.destination as? PokemonViewController,
                let index = tableView.indexPathForSelectedRow?.row {
            destination.url = pokemon[index].url
        } //HERE -> this closes the if-statement, not the method !!
    func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {

Just fix the curly braces. Also, note two things:

• filteredData variable contains Pokemon names which are lowercased (eg blastoise) so typing B will not reveal any results; you should adjust the logic here according to your needs
• you can consider trimming whitespaces in the text like let searchBarText = searchBar.text?.trimmingCharacters(in: .whitespacesAndNewlines) and then checking if searchBarText == "" { //... } else {...} to get rid of empty inputs and reload the data when cleared using the search bar's x button