我有一个显示购物 list 名称的 TableView Controller 。这些购物 list 是通过购物 list 类创建的,它让我可以指定购物 list 的名称和其中的项目。此 TableView 显示大约 5 个购物 list (名称)。当我按下一个时,我转到另一个 TableView Controller ,它显示了购物 list 的项目。但是,当我返 repo 物 list (名称) TableView Controller 并按下另一个购物 list 时,它仍然显示旧购物 list 中的商品,而不是被按下的商品。我想我已经将问题缩小到第二个 TableView Controller 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!
最佳答案
ViewDidLoad
在 ViewController 首次加载到内存时被调用一次。由于您的 ListsItemsViewController
是您的 ListViewController
的强大属性,并且您多次导航到它,所以没有任何东西告诉它更新其 View 或重新加载您的 tableview,因为它确实不会被释放(因此 ViewDidLoad
和 TableView
委托(delegate)/数据源方法不会被调用)。您还没有添加任何告诉它更新的自定义代码。
如果你想将这些 View Controller 保留为 ListViewController
的类属性,那么你可以在 ViewWillAppear
的方法中添加 tableView.reloadData
ListsItemsViewController
如下所示。
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
}
}
另一种选择是删除那些惰性变量,并根据需要初始化那些 View Controller ,这样一旦您将它们从堆栈中删除,它们就会被释放。这意味着您的表格 View 将始终重新加载,而无需在 ViewWillAppear
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)
]
//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() {
let newListVC = NewListViewController()
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) {
let listItemsVC = ListItemsViewController()
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
}
}
关于ios - TableView 中的 cellForRowAt 未更新,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/48411864/