想使用数据模型按用户姓氏进行索引 table 视图排序，但无法理解如何

Question

我是新手，所以这个问题可能很愚蠢。我制作了一些带有用户名的索引 table 视图。现在我添加了一个带有用户姓氏的标签，我想使用数据模型使我的索引 table 视图按用户姓氏排序，但我真的不知道该怎么做。这可能会有所帮助，因此 here 您可以立即查看我的应用程序的运行情况。首先，有 FriendsSearchViewController 所有用户模板。

import UIKit

final class FriendsSearchViewController: UITableViewController {

    var friends = [
        "Polina",
        "Ivan",
        "Pavel",
        "Maria",
        "Nick"
    ]
    
    var userFriends: [String] = []
    var friendSectionTitles = [String]()
    var friendsDictionary = [String: [String]]()

    // MARK: - Lifecycle
    override func viewDidLoad() {
        super.viewDidLoad()
        tableView.register(UINib(
            nibName: "FriendCell",
            bundle: nil),
                           forCellReuseIdentifier: "friendCell")
        
        for friend in friends {
            let friendKey = String(friend.prefix(1))
            if var friendValues = friendsDictionary[friendKey] {
                friendValues.append(friend)
                friendsDictionary[friendKey] = friendValues
            } else {
                friendsDictionary[friendKey] = [friend]
            }
        }
        
        friendSectionTitles = [String](friendsDictionary.keys)
        friendSectionTitles = friendSectionTitles.sorted(by: { [=11=] <  })
    }
    
    // MARK: - Table view data source
    
    override func numberOfSections(in tableView: UITableView) -> Int {
        friendSectionTitles.count
    }
    
    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        let friendKey = friendSectionTitles[section]
        if let friendValues = friendsDictionary[friendKey] {
            return friendValues.count
        }
        
        return 0
    }
    
    override func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
        friendSectionTitles[section]
    }
    
    override func sectionIndexTitles(for tableView: UITableView) -> [String]? {
        friendSectionTitles
    }
    
    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        guard
            let cell = tableView.dequeueReusableCell(withIdentifier: "friendCell", for: indexPath) as? FriendCell
        else { return UITableViewCell() }
        
        var currentFriend = friends[indexPath.row]
        
        let friendKey = friendSectionTitles[indexPath.section]
        if let friendValues = friendsDictionary[friendKey] {
            currentFriend = friendValues[indexPath.row]
        }

        cell.configure(
            photo: UIImage(named: "\(indexPath.row)") ?? UIImage(),
            name: currentFriend,
            surname: "")

        return cell
    }

    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        
        defer {
            tableView.deselectRow(at: indexPath, animated: true)
        }
        
        let friendKey = friendSectionTitles[indexPath.section]
        var currentFriend = ""
        if let friendValues = friendsDictionary[friendKey] {
            currentFriend = friendValues[indexPath.row]
        }
        
        if userFriends.firstIndex(of: currentFriend) == nil {
            userFriends.append(currentFriend)
        }
        
        self.performSegue(withIdentifier: "addFriend", sender: nil)
    }
    
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
            if segue.identifier == "addFriend",
               let myFriendsViewController = segue.destination as? MyFriendsViewController {
                myFriendsViewController.friends = userFriends
        }
    }
}

并且有 MyFriendsViewController 的用户已添加到好友列表：

import UIKit

final class MyFriendsViewController: UITableViewController {
    var friends = [String]() {
        didSet {
            //
        }
    }
    
    
    @IBAction func addFriend(segue: UIStoryboardSegue) {
        guard segue.identifier == "addFriend",
            let allFriendsViewController = segue.source as? FriendsSearchViewController
        else { return }
        friends = allFriendsViewController.userFriends
        tableView.reloadData()
    }
    
    // MARK: - Lifecycle
    override func viewDidLoad() {
        super.viewDidLoad()
        tableView.register(UINib(
            nibName: "FriendCell",
            bundle: nil),
                           forCellReuseIdentifier: "friendCell")
    }
    
    // MARK: - Table view data source
    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        friends.count
    }
    
    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        guard
            let cell = tableView.dequeueReusableCell(withIdentifier: "friendCell", for: indexPath) as? FriendCell
        else { return UITableViewCell() }
        
        let currentFriend = friends[indexPath.row]

        cell.configure(
            photo: UIImage(named: "\(indexPath.row)") ?? UIImage(),
            name: currentFriend,
            surname: "")

        return cell
    }
    
    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        defer { tableView.deselectRow(
            at: indexPath,
            animated: true)}
        performSegue(
            withIdentifier: "showProfile",
            sender: nil)
    }
    
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "addFriend",
           let allFriendsViewController = segue.destination as? FriendsSearchViewController {
            allFriendsViewController.userFriends = friends
        }
    }
}

还有 UserModel 可能看起来不正确：

import UIKit

struct UserModel {
    let userName: String
    let userSurname: String
    let userPhoto: UIImage
    let userAge: String
}

和 FriendCell 单元格配置：

import UIKit

class FriendCell: UITableViewCell {
    @IBOutlet var friendPhoto: AvatarImage!
    @IBOutlet var friendName: UILabel!
    @IBOutlet var friendSurname: UILabel!
    
    func configure(
        photo: UIImage,
        name: String,
        surname: String) {
            self.friendPhoto.image = photo
            self.friendName.text = name
            self.friendSurname.text = surname
        }
}

我无法想象我该怎么办。我应该怎么做？拜托，你能给我一些代码示例的想法吗？谢谢！

Answer 1

1.

对 UserModel

进行一些小的调整

// Make UserModel conform to Equatable protocol so you can
// compare two UserModel Objects using == or firstIndexOf
// Read more on Equatable here: https://developer.apple.com/documentation/swift/equatable
struct UserModel: Equatable {
    // I changed this to userFirstName to be more clear
    let userFirstName: String
    
    let userSurname: String
    
    // I made UIImage? optional, but you can change if you wish
    let userPhoto: UIImage?
    
    let userAge: Int
}

2.

将结构添加到数组而不是 FriendsSearchViewController

中的字符串

// Update friends array to hold structs of people
var friends = [
    UserModel(userFirstName: "Polina",
              userSurname: "James",
              userPhoto: UIImage(systemName: "star"),
              userAge: 20),
    UserModel(userFirstName: "Ivan",
              userSurname: "Gomez",
              userPhoto: UIImage(systemName: "star"),
              userAge: 20),
    UserModel(userFirstName: "Pavel",
              userSurname: "Harvey",
              userPhoto: UIImage(systemName: "star"),
              userAge: 20),
    UserModel(userFirstName: "Maria",
              userSurname: "Fernando",
              userPhoto: UIImage(systemName: "star"),
              userAge: 20),
    UserModel(userFirstName: "Nick",
              userSurname: "Cage",
              userPhoto: UIImage(systemName: "star"),
              userAge: 20),
    UserModel(userFirstName: "Shawn",
              userSurname: "Frank",
              userPhoto: UIImage(systemName: "star"),
              userAge: 20)
]

3.

将这些更改为结构数组，而不是 FriendsSearchViewController

中的字符串

// userFriends should now be an array of UserModel type, not String
var userFriends: [UserModel] = []
var friendSectionTitles = [String]()

// Also friendsDictionary should be an array of UserModel type, not String
var friendsDictionary = [String: [UserModel]]()

4.

调整 viewDidLoad 中的循环以使用结构，因为它们在 FriendsSearchViewController

中不再是字符串

// Now friend will be of type UserModel, not string
for friend in friends {
    
    // So we need to check the prefix of the UserMode.userSurname
    let friendKey = String(friend.userSurname.prefix(1))
    
    if var friendValues = friendsDictionary[friendKey] {
        friendValues.append(friend)
        friendsDictionary[friendKey] = friendValues
    } else {
        friendsDictionary[friendKey] = [friend]
    }
}

friendSectionTitles = [String](friendsDictionary.keys)
friendSectionTitles = friendSectionTitles.sorted(by: { [=13=] <  })

5. 调整 tableView 数据源函数以使用结构而不是字符串

在两个 ViewControllers

中修复此行 cellForRowAt

// Now you need to get the UserModel.userFirstName and UserModel.userSurname
cell.textLabel?.text = "\(currentFriend.userFirstName) \(currentFriend.userSurname)"

在 FriendsSearchViewController

中修复 didSelectRowAt 中的这一行

// This should not be a string
var currentFriend = friends[indexPath.row]

6.

在 MyFriendsViewController

中将朋友数组从字符串更改为 UserModel

var friends = [UserModel]() {
    didSet {
        //
    }
}

7. 现在要按姓氏对朋友列表进行排序，请调整退出 segue 函数以对朋友数组进行排序

@IBAction func addFriend(segue: UIStoryboardSegue) {
    guard segue.identifier == "addFriend",
        let allFriendsViewController = segue.source as? FriendsSearchViewController
    else { return }
    
    // Sort data when you come back
    friends = allFriendsViewController.userFriends.sorted {
        [=17=].userSurname < .userSurname
    }
    
    tableView.reloadData()
}

这应该会给你想要的结果

但是，请阅读这些主题以充分掌握这些概念：

Structs & Classes

Equatable

Sorting arrays

最后的建议是将您的问题分解成更小的部分，同时解决堆栈溢出问题。

例如这里有几个不同的主题，例如如何创建模型、如何将结构与数组一起使用、如何对数组进行排序。

每个问题有一个主题将帮助您更快地得到答案，但您尝试做事并提出问题是件好事。

想使用数据模型按用户姓氏进行索引 table 视图排序，但无法理解如何

Wanna do indexed table view sorting by user's surname using data model, but cannot understand how

uikit

swift