在另一个 class (scene.swift) 中引用我的视图控制器 - 所有变量都变为空？ Swift 3

Question

我正在尝试从我的 Scene.swift class 中的视图控制器调用方法 - 我能够做到。当我点击在我的视图控制器中设置的 SKLabel 节点时调用 touchesBegan 方法后调用该方法。

问题是当我点击一个 SKLabelNode 时，控制传递给 Scene.swift class 并且在 touchesBegan 方法中，调用了我想调用的方法，所以控制被传递回到视图控制器，当我回到这里时，似乎我所有的变量都设置为 nil，好像它是一个完全不同的控制器实例？

当我尝试在 ArViewController 中设置标签的文本属性时，checkIfValidTime 方法中出现错误。 - 我用 ** 突出显示了这些行。

错误：

Fatal error: Unexpectedly found nil while unwrapping an Optional value

如何引用视图控制器的相同实例，以便在 Scene.Swift 中声明时变量不会重置？或者有什么方法可以在视图控制器中实现 touchesBegan 方法，这样我就不必实例化 ARViewController 了吗？

对于此事，我将不胜感激，因为我已经被困了一段时间，而且我是 iOS 和 swift 应用程序设计的新手。

我已尝试将代码限制在解释此问题所需的范围内。有任何问题就问。谢谢

ARViewController:

    public var receivedCallback : Bool = false

    class ARViewController: UIViewController, ARSKViewDelegate, URLSessionDelegate {
        // MARK: - IBOutlets
        @IBOutlet weak var sceneView: ARSKView!
        @IBOutlet weak var guideLabel: UILabel!
        @IBOutlet weak var testLbl: UILabel!

 var scene : Scene?
        static var dateToUse : Date?
        var aRLocalDate : Date?

        var button: SKSpriteNode?

        override func viewDidLoad() {
            super.viewDidLoad()
        }

        override func viewDidAppear(_ animated: Bool) {
            super.viewDidAppear(animated)
            /*
             Start the view's AR session with a configuration that uses the rear camera,
             device position and orientation tracking, and plane detection..
             */
            let configuration = ARWorldTrackingConfiguration()

            guard ARWorldTrackingConfiguration.isSupported else {
                fatalError(""
                    ARKit is not available on this device."")
            }
            sceneView.session.run(configuration)
            sceneView.delegate = self
            if let scene = SKScene(fileNamed: "Scene"){
                self.scene = scene as! Scene
                sceneView.presentScene(self.scene)
            } else {
                print("Error: scene initalisation failed")
            }
            let overflow = ((aRLocalDate?.debugDescription.count)! - 11)
            let endIndex = aRLocalDate?.debugDescription.index((aRLocalDate?.debugDescription.endIndex)!, offsetBy: -overflow)
            if let truncatedDate = aRLocalDate?.debugDescription.substring(to: endIndex!){
                DateLabel.text = truncatedDate
            }  
        }

        **/// - Tag: PlaceARContent**
        func view(_ view : ARSKView, nodeFor anchor: ARAnchor) -> SKNode? {
            if self.Generated == false{
                self.guideLabel.alpha = 0
                parentNode = SKShapeNode(rectOf: CGSize(width: 400, height: 720))
                var count = 1;
                for time in timesArray {
                    **//add a SKSpriteNode and assign image to it**
                    **let labelNode : SKLabelNode = SKLabelNode(text: time)**
                    labelNode.name = "booklabel" + String(count)
                    labelNode.isUserInteractionEnabled = false;
                    parentNode?.addChild(labelNode)
                    posy -= 60
                    count += 1
                }
                parentNode?.alpha = 0.6
                self.Generated = true

                drawEventNodes()
                return parentNode
            }
            else {
                return nil
            }
        }

        //check if the booking is not in the past
        func checkIfValidTime(bookingTime: String, startDateTimeDate: Date) -> Bool {
            thisDate = ARViewController.dateToUse;
            let date = Date()
            let currentHour = Calendar.current.component(.hour, from: date)
            if (startDateTimeDate > date) {
                print("Start time is greater than the current date. = valid")
               **self.guideLabel.text = "Test"**
                return true;
            }
            else {
                print("Start time is not valid - before current time")
                **self.guideLabel.text = "Test"**
                return false;
            }
        }

        func doPost(bookingTime: String) {
            print("Start of post method")
            thisDate = ARViewController.dateToUse;
            roomToBook = globalVariables.roomDictionary[globalVariables.userString]!
            let name = globalVariables.userString;
            let date = Date()
            let dateFormatter = DateFormatter()
            dateFormatter.dateFormat = "yyyy-MM-dd"
            let displayName = globalVariables.userString
            let startDateStr = dateFormatter.string(from: thisDate!)
            let startHourString = bookingTime
            print("StartDateStr:", startDateStr)
            dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss"
            let startDateTimeString = "\(startDateStr)T\(startHourString)"
            let startDateTimeDate = dateFormatter.date(from: startDateTimeString)
            let endDateTimeDate = startDateTimeDate?.addingTimeInterval(3600)//3600 = 1 hour
            let endDateTimeString = dateFormatter.string(from: endDateTimeDate!)
            print("Start Date Time String", startDateTimeString)
            print("End date time string", endDateTimeString)
            print ("room to book: ",roomToBook)

            let valid = checkIfValidTime(bookingTime: bookingTime, startDateTimeDate: startDateTimeDate!)

            if (valid == true) {
                let jsonObject: [String: Any] =
                    [
                        "subject": "Booking",
                        "body":[
                            "contentType": "HTML",
                            "content": "Test Booking"
                        ],
                        "start":[
                            "dateTime": startDateTimeString,
                            "timeZone": "UTC"
                        ],
                        "end": [
                            "dateTime": endDateTimeString,
                            "timeZone": "UTC"
                        ],
                        "location":[
                            "displayName": displayName
                        ],
                        "attendees":[[
                            "emailAddress": [
                                "address": roomToBook,
                                "name": displayName
                            ],

                            "type": "required"
                            ]]
                ]

                //let valid = JSONSerialization.isValidJSONObject(jsonObject) // true
                let jsonData = try? JSONSerialization.data(withJSONObject: jsonObject)

                // create post request
                let url = URL(string: "https://graph.microsoft.com/v1.0/me/events")!

                var request = URLRequest(url: url)
                request.setValue("Bearer \(globalVariables.accessToken)", forHTTPHeaderField: "Authorization")
                request.setValue("application/json; charset=utf-8", forHTTPHeaderField: "Content-Type")
                request.setValue("application/json; charset=utf-8", forHTTPHeaderField: "Accept")        // the expected response is also JSON
                request.httpMethod = "POST"

                // insert json data to the request
                request.httpBody = jsonData

                let task = URLSession.shared.dataTask(with: request) { data, response, error in
                    guard let data = data, error == nil else {
                        print(error?.localizedDescription ?? "No data")
                        return
                    }
                    let responseJSON = try? JSONSerialization.jsonObject(with: data, options: [])
                    if let responseJSON = responseJSON as? [String: Any] {
                        print(responseJSON)
                    }
                }

                task.resume()
                print("Post Done")
                print("Refreshing now")
                //code to refresh?

            }
            else {
                print("Invalid booking time - it is in the past.")
            }
        }

Scene.Swift:

class Scene : SKScene{
    var controller = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "ARStoryBoard") as! ARViewController
   // var controller: ARViewController!
    var bookingTime : String?

    override func touchesBegan(_ touches: Set<UITouch>, with event : UIEvent?) {
       // var c =  self.view?.window?.rootViewController as! ARViewController;

        for touch in touches {
            let location = touch.location(in: self)
            let node : SKNode = self.atPoint(location)
            let name = node.name
            switch name {
            case "booklabel1"?:
                controller.doPost(bookingTime: "08:00:00")
            case "booklabel2"?:
                controller.doPost(bookingTime: "09:00:00")
            case "booklabel3"?:
                controller.doPost(bookingTime: "10:00:00")
            case "booklabel4"?:
                controller.doPost(bookingTime: "11:00:00")
            case "booklabel5"?:
                controller.doPost(bookingTime: "12:00:00")
            case "booklabel6"?:
                controller.doPost(bookingTime: "13:00:00")
            case "booklabel7"?:
                controller.doPost(bookingTime: "14:00:00")
            case "booklabel8"?:
                controller.doPost(bookingTime: "15:00:00")
            case "booklabel9"?:
                controller.doPost(bookingTime: "16:00:00")
            case "booklabel10"?:
                controller.doPost(bookingTime: "17:00:00")
            case "booklabel11"?:
                controller.doPost(bookingTime: "18:00:00")
            default:
                print ("No Specific Label Clicked")
            }
        }
    }

}

Answer 1

试试这个。（检查更新后的编辑答案：强烈推荐）

ARViewController：在class

之外创建一个实例

weak var arViewControllerInstance = ARViewController()

确保在 ARViewController 内部初始化 class:

 override func viewDidLoad() {
            super.viewDidLoad()
            arViewControllerInstance = self
        }

现在您可以调用 Scene.Swift 使用：

arViewControllerInstance?.doPost(bookingTime: "08:00:00")

Edited: Highly recommended

以上方法简单但强烈不推荐用于最佳实践。看看下面使用委托协议的实现。

创建协议

protocol ScenceArViewControllerDelegate {
    func doPost(bookingTime: String)
}

在 ARViewController class 中添加 Above 委托，如下所示。

class ARViewController: UIViewController, ScenceArViewControllerDelegate{
    func doPost(bookingTime: String){
       //Funcion body goes here
    }
}

在场景中创建一个委托变量 class 如下 (Scene.swift)

class Scene: SKScene{
    weak var delegateARVC: ScenceArViewControllerDelegate?
}

首先实施。现在你已经声明了来自 ARViewController 的 delegateARVC 变量，如下面的代码。（注意：您可以使用依赖注入来设置值，但下面只是设置对象）

class ARViewController: UIViewController, ScenceArViewControllerDelegate{

        var scene: Scene?
 
        override func viewDidLoad() {
            super.viewDidLoad()
            scene = Scene()
            scene.delegateARVC = self
        }

        func doPost(bookingTime: String){
           //Funcion body goes here
        }
    }

现在一切都很好。现在您的场景 class 知道它与 ARViewController 有一个关系引用，方法是使用 ScenceArViewControllerDelegate.

调用的 doPost

您可以从场景 class.

中调用 AARViewController 的 doPost 方法，如下所示

guard let delegateARCAvailable = delegateARVC else { return }
delegateARCAvailable.doPost(bookingTime: "08:00:00")

想申请就申请吧。谢谢。

Answer 2

@Liam 有 'chain of ownership'。 "Own" 表示负责保持对象存活。示例库、Reader 和书籍。书上有图书馆的印章，所以它可以参考它，但绝对书不拥有图书馆。 reader 也一样。但是 Library 和 Reader 都声称拥有这本书的所有权。如果没有人拿书去读并声明所有权），并且图书馆被销毁 - 他们的书也被销毁。

在Swift中，它是通过strong和weak引用实现的。默认情况下，所有变量都是 strong。

通常您会查看由应用委托或其他视图控制器（手动或使用故事板）实例化的控制器。任何其他人都可以被视图控制器使用，并且可以知道 viewcontroller 但不会 "own" 它。所以变量必须声明为 weak。请注意，您不拥有 weak，因此它必须是可选的并且可以随时取消（如果用户向后导航），因此您必须使用额外的保护措施。

总结一下：

1: 在场景中声明你的 viewController 弱：

class Scene : SKScene{
    weak var controller: ARViewController?
    ....*
}

2：为您的场景提供视图控制器。您可以在创建场景或设置场景时执行此操作。例如：

 class ARViewController: UIViewController, ARSKViewDelegate, URLSessionDelegate {
 //...
 var scene : Scene? {
    didSet{
       //Optional: In case you can change scenes - remove view controller from old scene 
       oldValue?.controller = nil
       //Actually set view controller of any scene it "own"
       scene?.controller = self
    }
 }

PS：有附加修饰符"unowned"。但这是更先进的技术，可能会导致问题和崩溃。我建议您熟悉 weak。习惯 guard 保留循环，然后继续。

在另一个 class (scene.swift) 中引用我的视图控制器 - 所有变量都变为空？ Swift 3

Referring to my view controller in another class (scene.swift) - all variables turn to null? Swift 3

scene

viewcontroller

touchesbegan

ios

swift