即使在使用 view.setNeedsDisplay() 刷新视图后，.isHidden 属性也不反映对视图的更改

Posted 2023-02-26

【中文标题】即使在使用 view.setNeedsDisplay() 刷新视图后，.isHidden 属性也不反映对视图的更改

【英文标题】：.isHidden property does not reflect changes to the view even after refreshing the view using view.setNeedsDisplay()

【发布时间】：2018-04-06 09:01:24

【问题描述】：

从应用程序委托接收到我传递一个静态字符串并使用set需要布局刷新movieDetailsViewController，功能和代码正常工作，但更改不会反映在视图中。

AppDelegate:-

let storyboard = UIStoryboard(name: "Main", bundle: nil)
                    let movieDetailsVC = storyboard.instantiateViewController(withIdentifier: "MovieDetailsViewController") as! MovieDetailsViewController




                        if (rootViewController?.isKind(of: MovieDetailsViewController.self))!
                        
                            if notificationContentType == 1
                            
                                movieDetailsVC.FROMPAGE = "FROMAPPDELEGATE"
                                movieDetailsVC.view.setNeedsDisplay()
                            
                        

视图控制器：-

override func viewDidLoad()
    
        super.viewDidLoad()

        let appDelegate: AppDelegate? = UIApplication.shared.delegate as? AppDelegate
        appDelegate?.read()

        if FROMPAGE == "FROMAPPDELEGATE"
        
//                self.updateUI()
            print("Function is Called")
            //print(self.view.frame)
            //self.view.setNeedsDisplay()

            let appDelegate: AppDelegate? = UIApplication.shared.delegate as? AppDelegate
            appDelegate?.read()


            var currentreleaseId : Int!
            var currentrentalType : Int!

            currentreleaseId = resultDictionaryFromFCM.value(forKey: "releaseId") as? Int
            let convertedId = String(currentreleaseId)
            currentrentalType = resultDictionaryFromFCM.value(forKey: "rentalType") as? Int
            let elapsedTime = resultDictionaryFromFCM.value(forKey: "elapsedTime") as? Float

            if convertedId == ApiClassStruct.RELEASEID
            
                let movieStartDate = resultDictionaryFromFCM.value(forKey: "clientStartTime") as? Double
                defaults.set(movieStartDate, forKey: "MOVIE_START_DATE")
                if currentrentalType == 1
                
                    defaults.set("true", forKey: "isStillPlaying")
                    self.tableViewOutlet.isHidden = true
                    self.seekBarOutlet.isHidden = false


                    let maximumDuration = defaults.integer(forKey: "MAXIMUMDURATION")
                    self.seekBarMaximumDurationLabelOutlet.text = self.convertTime(miliseconds: maximumDuration)
                    self.seekBarOutlet.maximumValue = Float(maximumDuration)

                    let currentDate = NSDate()
                    let dateFormatter = DateFormatter()
                    dateFormatter.dateFormat = "yyyy-MM-dd, HH:mm:ss"
                    dateFormatter.timeZone = NSTimeZone(name: "IST") as TimeZone!
                    let date = dateFormatter.date(from: dateFormatter.string(from: currentDate as Date))
                    let currentDATE = date!.timeIntervalSince1970 * 1000

                    let movieStartDate = defaults.value(forKey: "MOVIE_START_DATE") as? Double

                    let difference = currentDATE - movieStartDate!

                    self.seekBarOutlet.setValue(Float(difference), animated: true)
                    let selectedValue = "\(Int(self.seekBarOutlet.value))"
                    let convertedValue = self.convertTime(miliseconds: Int(selectedValue)!)
                    self.seekBarMinimumDurationLabelOutlet.text = convertedValue

                    self.myTimer =  Timer.scheduledTimer(timeInterval:1, target: self, selector: #selector(self.updateSlider), userInfo: nil, repeats: true)

                    print("Play condition ended")
                

但是变化没有反映出来，在这个问题上停留了很长时间。

【问题讨论】：

您所说的更改未反映是什么意思？你确认在设置movieDetailsVC.FROMPAGE = "FROMAPPDELEGATE"之前没有调用viewDidLoad吗？

它没有被调用，它是在我在 appDelegate 中编写的 movieDetailsVC.setNeedsDisplay() 之后调用的。通过没有反映的更改，我的意思是如果条件为真，应该显示 seekBarView 但不应该隐藏 tableView 但不会隐藏。

显示代码如何呈现movieDetailsVC

当我收到通知时，在 appDelegate 中检查了条件，我调用了 setNeedsDisplay() 我想更新或说它，因为我想刷新视图，只需要来回刷新。

let movieDetailsVC = storyboard.instantiateViewController(withIdentifier: "MovieDetailsViewController") as! MovieDetailsViewController 创建一个新对象。您正在对这个新对象进行设置。如果实例已经存在，则不会受到影响。

【参考方案1】：

let movieDetailsVC = storyboard.instantiateViewController(withIdentifier: "MovieDetailsViewController") as! MovieDetailsViewController

创建MovieDetailsViewController 的新实例，并对其进行修改。如果您不提供该实例，则不会看到任何更改。如果您已经提交了MovieDetailsViewController实例，则提交的实例将不受其影响。

我建议使用通知来通知MovieDetailsViewController 更新其 UI。

例如，在应用程序委托中使用它来创建和发布新通知：

NotificationCenter.default.post(name: NSNotification.Name("movieDetailsUpdateNotif"),
                                object: self, userInfo: nil)

然后在MovieDetailsViewController.viewDidLoad注册收听这些通知：

override func viewDidLoad() 
    super.viewDidLoad()

    NotificationCenter.default.addObserver(self,
                                           selector: #selector(receiveNotification(notification:)),
                                           name: NSNotification.Name("movieDetailsUpdateNotif"),
                                           object: nil)

要清理它，请在deinit 中注销（只是为了表现得好）：

deinit 
    NotificationCenter.default.removeObserver(self)

最后，实现MovieDetailsViewController.receiveNotification(notification:)来处理通知：

@objc fileprivate func receiveNotification(notification: NSNotification) 
    // update UI here, e.g. hide things, show other, etc.
    // this will be called when AppDelegate creates a and posts that notification