TableView中的cellForRowAt未更新

时间：2018-01-23 22:27:18

标签： ios uitableview swift4

我有一个表视图控制器，显示购物清单的名称。这些购物清单是通过购物清单类创建的，该类允许我指定购物清单的名称及其中的项目。此表视图显示大约5个购物清单（名称）。当我按下一个时，我会转到另一个表视图控制器，它显示购物清单的项目。但是，当我返回购物清单（名称）表格视图控制器并按下另一个购物清单时，它仍然显示旧购物清单中的商品，而不是按下的商品。我想我已经把问题缩小到第二个表视图控制器的cellForItemAt没有被再次调用。

import UIKit

class List: NSObject {

    var name: String
    var items: [String?]
    var shared: String?

    init(name: String, items: [String], shared: String?) {
        self.name = name
        self.items = items
        self.shared = shared
    }

}

enum ListType {
    case apply
    case view
}

class ListViewController: UITableViewController {

    //Initialize Variables Here
    let cellId = "cellId"

    var lists: [List] = [
        List(name: "Veggies", items: ["Fruit Loops", "Pasta"], shared: nil),
        List(name: "11/17/18", items: ["Eggs", "Green Beans", "Pirate Booty", "Bread", "Milk"], shared: nil),
        List(name: "Fruits", items: ["Fruit Loops", "Oranges"], shared: nil),
        List(name: "Red Foods", items: ["Apples", "Tomatoes", "Watermelon", "Cherries"], shared: nil),
        List(name: "Grains", items: ["Bread Crumbs", "Pasta", "Rice", "Chicken Flavored Rice"], shared: nil)
    ]

    //Create Class Lazy Vars
    lazy var newListVC: NewListViewController = {
        let launcher = NewListViewController()
        //        launcher.homeController = self
        return launcher
    }()

    lazy var listItemsVC: ListItemsViewController = {
        let launcher = ListItemsViewController()
        //        launcher.homeController = self
        return launcher
    }()

    //Setup Enums and Switches
    var listType: ListType!


    override func viewDidLoad() {
        super.viewDidLoad()

        //Things that both cases have in common:
        navigationController?.navigationBar.prefersLargeTitles = true

        let addBarButtonItem = UIBarButtonItem(title: "+", style: .plain, target: self, action: #selector(newList)) //+ Button
        addBarButtonItem.setTitleTextAttributes([NSAttributedStringKey.font: UIFont(name: "HelveticaNeue-Light", size: 27)!], for: .normal)
        addBarButtonItem.setTitleTextAttributes([NSAttributedStringKey.font: UIFont(name: "HelveticaNeue-Light", size: 27)!], for: .selected)

        //SWITCH STATEMENT
        switch listType as ListType {

        case ListType.apply:
            //Apply Begin
            navigationItem.title = "Apply List"

            //Setup Navigation Bar Items
            let locateBarButtonItem = UIBarButtonItem(title: "Locate Item", style: .plain, target: self, action: nil)

            //Add items to navigation bar
            navigationItem.rightBarButtonItems = [addBarButtonItem, locateBarButtonItem]
            //Apply End
        case ListType.view:
            //View Begin
            //Setup Navigation Bar
            navigationItem.title = "My Lists"

            //Add items to navigation bar
            navigationItem.rightBarButtonItem = addBarButtonItem
            navigationItem.leftBarButtonItem = editButtonItem

            //View End
        }
        //SWITCH STATEMENT END


        //Register TableView with Id: cellId
        tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellId)

    }

    @objc func newList() {
        newListVC.pageControlFunc(pageView: PageView.name)
        navigationController?.pushViewController(newListVC, animated: true) //Then pushes listVC
    }

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

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath)

        cell.textLabel?.text = self.lists[indexPath.row].name //Then sets cell of indexPath text = lists value of index path

        return cell
    }

    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        listItemsVC.listName = lists[indexPath.row].name
        listItemsVC.listItems = lists[indexPath.row].items
        print(listItemsVC.listItems)
        navigationController?.pushViewController(listItemsVC, animated: true)
    }

}


///////////////////////////////////////////////////////////////////////////

SECOND UITABLEVIEW - NOT UPDATING

///////////////////////////////////////////////////////////////////////////

import UIKit

class ListItemsViewController: UITableViewController {

    //Initialize Variables Here
    let cellId = "cellId1"

    var listName: String?
    var listItems: [String?] = []


    override func viewDidLoad() {
        super.viewDidLoad()

        //Things that both cases have in common:
        navigationController?.navigationBar.prefersLargeTitles = true

        //Set Title
        navigationItem.title = listName

        //Register TableView with Id: cellId
        tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellId)

        //Delegate method not called on push to view

    }

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

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath)

        cell.textLabel?.text = listItems[indexPath.row] //Then sets cell of indexPath text = lists value of index path

        return cell
    }

}

提前致谢！

1 个答案:

答案 0 :(得分：1)

当ViewController首次加载到内存中时，

ViewDidLoad被调用一次。由于您ListsItemsViewController上的ListViewController是一个强大的属性，并且您多次导航到它，因此没有任何东西告诉它更新其视图或重新加载您的tableview，因为它没有被解除分配（所以{不会调用{1}}和ViewDidLoad委托/数据源方法。您还没有添加任何自定义代码来告知它更新。

如果您希望将这些视图控制器保留为TableView的类属性，则可以在ListViewController tableView.reloadData方法中添加ViewWillAppear，如下所示。

ListsItemsViewController

另一个选项是删除那些惰性变量，并根据需要初始化这些视图控制器，以便在从堆栈中删除它们后将其取消分配。这意味着您的tableviews将始终重新加载，而无需在import UIKit class List: NSObject { var name: String var items: [String?] var shared: String? init(name: String, items: [String], shared: String?) { self.name = name self.items = items self.shared = shared } } enum ListType { case apply case view } class ListViewController: UITableViewController { //Initialize Variables Here let cellId = "cellId" var lists: [List] = [ List(name: "Veggies", items: ["Fruit Loops", "Pasta"], shared: nil), List(name: "11/17/18", items: ["Eggs", "Green Beans", "Pirate Booty", "Bread", "Milk"], shared: nil), List(name: "Fruits", items: ["Fruit Loops", "Oranges"], shared: nil), List(name: "Red Foods", items: ["Apples", "Tomatoes", "Watermelon", "Cherries"], shared: nil), List(name: "Grains", items: ["Bread Crumbs", "Pasta", "Rice", "Chicken Flavored Rice"], shared: nil) ] //Create Class Lazy Vars lazy var newListVC: NewListViewController = { let launcher = NewListViewController() // launcher.homeController = self return launcher }() lazy var listItemsVC: ListItemsViewController = { let launcher = ListItemsViewController() // launcher.homeController = self return launcher }() //Setup Enums and Switches var listType: ListType! override func viewDidLoad() { super.viewDidLoad() //Things that both cases have in common: navigationController?.navigationBar.prefersLargeTitles = true let addBarButtonItem = UIBarButtonItem(title: "+", style: .plain, target: self, action: #selector(newList)) //+ Button addBarButtonItem.setTitleTextAttributes([NSAttributedStringKey.font: UIFont(name: "HelveticaNeue-Light", size: 27)!], for: .normal) addBarButtonItem.setTitleTextAttributes([NSAttributedStringKey.font: UIFont(name: "HelveticaNeue-Light", size: 27)!], for: .selected) //SWITCH STATEMENT switch listType as ListType { case ListType.apply: //Apply Begin navigationItem.title = "Apply List" //Setup Navigation Bar Items let locateBarButtonItem = UIBarButtonItem(title: "Locate Item", style: .plain, target: self, action: nil) //Add items to navigation bar navigationItem.rightBarButtonItems = [addBarButtonItem, locateBarButtonItem] //Apply End case ListType.view: //View Begin //Setup Navigation Bar navigationItem.title = "My Lists" //Add items to navigation bar navigationItem.rightBarButtonItem = addBarButtonItem navigationItem.leftBarButtonItem = editButtonItem //View End } //SWITCH STATEMENT END //Register TableView with Id: cellId tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellId) } @objc func newList() { newListVC.pageControlFunc(pageView: PageView.name) navigationController?.pushViewController(newListVC, animated: true) //Then pushes listVC } override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { return lists.count } override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath) cell.textLabel?.text = self.lists[indexPath.row].name //Then sets cell of indexPath text = lists value of index path return cell } override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { listItemsVC.listName = lists[indexPath.row].name listItemsVC.listItems = lists[indexPath.row].items print(listItemsVC.listItems) navigationController?.pushViewController(listItemsVC, animated: true) } } /////////////////////////////////////////////////////////////////////////// SECOND UITABLEVIEW - NOT UPDATING /////////////////////////////////////////////////////////////////////////// import UIKit class ListItemsViewController: UITableViewController { //Initialize Variables Here let cellId = "cellId1" var listName: String? var listItems: [String?] = [] override func viewDidLoad() { super.viewDidLoad() //Things that both cases have in common: navigationController?.navigationBar.prefersLargeTitles = true //Set Title navigationItem.title = listName //Register TableView with Id: cellId tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellId) //Delegate method not called on push to view } //This will always get called when this view controller's view is added to the window //so you can guarantee it will call your delegate methods to reload the tableView with your new data override func viewWillAppear(animated: Bool) { super.viewWillAppear(animated: animated) tableView.reloadData() } override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { return listItems.count } override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath) cell.textLabel?.text = listItems[indexPath.row] //Then sets cell of indexPath text = lists value of index path return cell } }

中添加任何代码 
ViewWillAppear
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