我正在使用 UICollectionView didSelectItemAt 来更新我在 HomeController 中设置的 UI 标签。所以基本上当我按下单元格时，我希望我的文本被更新。但是文本没有更新，虽然我已经调试并且值发生了变化。我已经尝试了所有方法，包括 setNeedsDisplay() 和通过 main thread 运行(它已经这样做了)
我在这些类中有很多代码(我不使用 storyboard)但这是标签设置(位于 HomeController 中):
import UIKit
import CoreData
class mainHomeController: UICollectionViewController, UICollectionViewDelegateFlowLayout {
static let sharedInstance = HomeController()
override func viewDidLoad() {
super.viewDidLoad()
setupBasketBar()
}
let totNumber: UILabel = {
let label = UILabel()
label.text = "0"
label.numberOfLines = 2
return label
}()
func setupBasketBar() {
self.view.addSubview(totNumber)
totNumber.translatesAutoresizingMaskIntoConstraints = false
totNumber.leadingAnchor.constraint(equalTo: view.leadingAnchor,constant: 330).isActive = true
totNumber.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
totNumber.bottomAnchor.constraint(equalTo: view.bottomAnchor,constant: 0).isActive = true
totNumber.heightAnchor.constraint(equalTo: view.heightAnchor,multiplier: 5).isActive = true
}
}
这位于提要单元格中:
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
HomeController.sharedInstance.totNumber.text = ("234")
HomeController.sharedInstance.totNumber.setNeedsDisplay()
}
我已经删除了相关部分。
这是 HomeController 的完整代码:
import UIKit
import CoreData
class HomeController: UICollectionViewController, UICollectionViewDelegateFlowLayout {
static let sharedInstance = HomeController()
let cellId = "cellId"
let trendingCellId = "trendingCellId"
let subscriptionCellId = "subscriptionCellId"
let titles = ["Home", "Trending", "Subscriptions", "Account"]
override func viewDidLoad() {
super.viewDidLoad()
navigationController?.navigationBar.isTranslucent = false
let titleLabel = UILabel(frame: CGRect(x: 0, y: 0, width: 30, height: view.frame.height))
titleLabel.text = "Home"
titleLabel.textColor = UIColor.black
titleLabel.font = UIFont.systemFont(ofSize: 20)
navigationItem.titleView = titleLabel
setupCollectionView()
setupMenuBar()
setupBasketBar()
}
func setupCollectionView() {
if let flowLayout = collectionView?.collectionViewLayout as? UICollectionViewFlowLayout {
flowLayout.scrollDirection = .horizontal
flowLayout.minimumLineSpacing = 0
}
collectionView?.backgroundColor = UIColor.white
collectionView?.register(FeedCell.self, forCellWithReuseIdentifier: cellId)
collectionView?.register(TrendingCell.self, forCellWithReuseIdentifier: trendingCellId)
collectionView?.register(SubscriptionCell.self, forCellWithReuseIdentifier: subscriptionCellId)
collectionView?.contentInset = UIEdgeInsetsMake(50, 0, 0, 0)
collectionView?.scrollIndicatorInsets = UIEdgeInsetsMake(50, 0, 0, 0)
collectionView?.isPagingEnabled = true
}
lazy var settingsLauncher: SettingsLauncher = {
let launcher = SettingsLauncher()
launcher.homeController = self
return launcher
}()
func handleMore() {
//show menu
settingsLauncher.showSettings()
}
func showControllerForSetting(_ setting: Setting) {
let dummySettingsViewController = UIViewController()
dummySettingsViewController.view.backgroundColor = UIColor.white
dummySettingsViewController.navigationItem.title = setting.name.rawValue
navigationController?.navigationBar.tintColor = UIColor.white
navigationController?.navigationBar.titleTextAttributes = [NSForegroundColorAttributeName: UIColor.white]
navigationController?.pushViewController(dummySettingsViewController, animated: true)
}
func handleSearch() {
scrollToMenuIndex(2)
}
func scrollToMenuIndex(_ menuIndex: Int) {
let indexPath = IndexPath(item: menuIndex, section: 0)
collectionView?.scrollToItem(at: indexPath, at: UICollectionViewScrollPosition(), animated: true)
setTitleForIndex(menuIndex)
}
fileprivate func setTitleForIndex(_ index: Int) {
if let titleLabel = navigationItem.titleView as? UILabel {
titleLabel.text = " \(titles[index])"
}
}
lazy var menuBar: MenuBar = {
let mb = MenuBar()
mb.homeController = self
return mb
}()
func buttonAction(sender: UIButton!) {
let btnsendtag: UIButton = sender
if btnsendtag.tag == 1 {
let storyboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let vc: UINavigationController = storyboard.instantiateViewController(withIdentifier: "NewViewController") as! UINavigationController
self.present(vc, animated: true, completion: nil)
}
}
let totLabel = UILabel(frame: CGRect(x: 0, y: 0, width: 200, height: 21))
let btn: UIButton = UIButton(frame: CGRect(x: 0, y: 600, width: 500, height: 80))
func setupBasketBar() {
//Checkout button
btn.backgroundColor = UIColor.rgb(36, green: 51, blue: 70)
btn.addTarget(self, action: #selector(buttonAction), for: .touchUpInside)
btn.tag = 1
self.view.addSubview(btn)
btn.setTitleColor(UIColor.yellow, for: .normal)
//Button that updates the current amount
totLabel.text = "Total amount"
totLabel.textColor = UIColor.white
self.view.addSubview(totLabel)
//constraints
totLabel.translatesAutoresizingMaskIntoConstraints = false
totLabel.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20).isActive = true
totLabel.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
totLabel.bottomAnchor.constraint(equalTo: view.bottomAnchor,constant: 0).isActive = true
totLabel.heightAnchor.constraint(equalTo: view.heightAnchor,multiplier: 0.1).isActive = true
//oldconstraints
/* self.view.addSubview(totNumber)
totNumber.translatesAutoresizingMaskIntoConstraints = false
totNumber.leadingAnchor.constraint(equalTo: view.leadingAnchor,constant: 330).isActive = true
totNumber.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
totNumber.bottomAnchor.constraint(equalTo: view.bottomAnchor,constant: 0).isActive = true
totNumber.heightAnchor.constraint(equalTo: view.heightAnchor,multiplier: 0.1).isActive = true*/
}
fileprivate func setupMenuBar() {
navigationController?.hidesBarsOnSwipe = false
let redView = UIView()
redView.backgroundColor = UIColor.rgb(36, green: 51, blue: 70)
view.addSubview(redView)
view.addConstraintsWithFormat("H:|[v0]|", views: redView)
view.addConstraintsWithFormat("V:[v0(50)]", views: redView)
view.addSubview(menuBar)
view.addConstraintsWithFormat("H:|[v0]|", views: menuBar)
view.addConstraintsWithFormat("V:[v0(50)]", views: menuBar)
menuBar.topAnchor.constraint(equalTo: topLayoutGuide.bottomAnchor).isActive = true
}
override func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
let index = targetContentOffset.pointee.x / view.frame.width
let indexPath = IndexPath(item: Int(index), section: 0)
menuBar.collectionView.selectItem(at: indexPath, animated: true, scrollPosition: UICollectionViewScrollPosition.centeredHorizontally)
setTitleForIndex(Int(index))
}
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 5
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let identifier: String
if indexPath.item == 1 {
identifier = trendingCellId
} else if indexPath.item == 2 {
identifier = subscriptionCellId
} else {
identifier = cellId
}
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: identifier, for: indexPath)
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: view.frame.width, height: view.frame.height - 50)
}
}
最佳答案
好的!查看更新后的代码片段，绝对不需要 sharedInstance 单例 - 我会完全删除它。
然后 didSelectItemAt 方法只需要是这样的:
override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
totNumber.text = "234"
}
关于ios - UILabel 文本即使具有新值也不会更新，已尝试一切，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/43230420/