即使在使用view.setNeedsDisplay（）刷新视图后，.isHidden属性也不会反映视图的更改

Posted 2021-05-04

从app delegate接收后我传递一个静态字符串并使用set needs Layout刷新movieDetailsViewController，函数和代码正常工作，但更改不会反映在视图中。

AppDelegate中： -

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")
                }
}

但这些变化并没有反映出来，长期坚持这个问题。

答案

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

创建MovieDetailsViewController的新实例，并修改它。如果您不提供该实例，则不会显示任何更改。如果您已经提供了MovieDetailsViewController实例，则所呈现的实例不会受其影响。

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

例如，在app delegate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注册以收听这些通知：

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中取消注册（只是表现得很好）：

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
}