初始化结构的实例并获取未解析的标识符错误

Question

我想在我的TableViewController中初始化一个名为TaskList的结构实例，但是我在每次使用“任务”的地方都遇到“使用未解析标识符“任务”错误。当我在类中声明var任务时，它运行良好，但是现在它是在另一个. swift文件中声明的var的初始化，我收到了这个错误。我刚刚在学习Swift，所以我怀疑这与架构有关，或者搞砸了如何从另一个文件调用对象。有人知道我需要做什么来修复它吗？非常感谢任何帮助！谢谢大家！

下面是 UITable 视图控制器代码：

import UIKit

class LoLFirstTableViewController: UITableViewController {

    //var tasks:[Task] = taskData
    // Hashed out the above line (even though it worked) because replacing with
    // the below line because trying to get instance of TaskList containing all
    // properties instead of just the tasks as well as to allow multiple instances
    // of TaskList

    let exampleList = TaskList(buddy: exampleBuddy, phoneNumber: examplePhoneNumber, tasks: exampleTaskData)

    override func viewDidLoad() {
        super.viewDidLoad()
        tableView.rowHeight = UITableViewAutomaticDimension
        tableView.estimatedRowHeight = 60.0
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

    override func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return tasks.count
    }

    @IBAction func cancelToLoLFirstTableViewController(_ segue:UIStoryboardSegue) {
    }

    @IBAction func saveAddTask(_ segue:UIStoryboardSegue) {
        if let AddTaskTableViewController = segue.source as? AddTaskTableViewController {

            if let task = AddTaskTableViewController.task {
                tasks.append(task)

                let indexPath = IndexPath(row: tasks.count-1, section: 0)
                tableView.insertRows(at: [indexPath], with: .automatic)
            }
        }
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "TaskCell", for: indexPath) as! TaskCell
        let task = tasks[indexPath.row]
            cell.task = task

        if cell.accessoryView == nil {
            let cb = CheckButton()
            cb.addTarget(self, action: #selector(buttonTapped(_:forEvent:)), for: .touchUpInside)
            cell.accessoryView = cb
        }
        let cb = cell.accessoryView as! CheckButton
        cb.check(tasks[indexPath.row].completed)

        return cell
    }

    func buttonTapped(_ target:UIButton, forEvent event: UIEvent) {
        guard let touch = event.allTouches?.first else { return }
        let point = touch.location(in: self.tableView)
        let indexPath = self.tableView.indexPathForRow(at: point)

        var tappedItem = tasks[indexPath!.row] as Task
        tappedItem.completed = !tappedItem.completed
        tasks[indexPath!.row] = tappedItem

        tableView.reloadRows(at: [indexPath!], with: UITableViewRowAnimation.none)
    }
}

如果有帮助的话，下面是TaskList结构的代码：

import UIKit

struct TaskList {
    var buddy: String?
    var phoneNumber: String?
    var tasks: [Task]

    init(buddy: String?, phoneNumber: String?, tasks: [Task]) {
        self.buddy = buddy
        self.phoneNumber = phoneNumber
        self.tasks = tasks
    }
}

Answer 1

在结构中，任务数组不是可选的，这意味着您必须传递一个初始化的任务数组。传递一个初始化的数组或将任务数组更改为可选数组，就像您对buddy和phoneNumber所做的那样。

import UIKit

struct TaskList {
var buddy: String?
var phoneNumber: String?
// add a question mark to make your array of tasks optional
var tasks: [Task]?

init(buddy: String?, phoneNumber: String?, tasks: [Task]) {
    self.buddy = buddy
    self.phoneNumber = phoneNumber
    self.tasks = tasks
  }
}

注意：当您使用struct时，您可以省略初始化程序，它会自动生成一个

import UIKit

struct TaskList {
   var buddy: String?
   var phoneNumber: String?
   var tasks: [Task]?
}

现在在您的视图中控制器初始化您的示例列表

// as your tasks array is optional now even if you pass in a nil it will not crash but it will not have a tasks array
let exampleList = TaskList(buddy: exampleBuddy, phoneNumber: examplePhoneNumber, tasks: exampleTaskData)

请记住在使用数组之前先将其展开，否则如果任务数组为零，应用程序可能会再次崩溃。出租或保护时使用

if let tasks = exampleList.tasks {
   // now you can use your tasks array
}