参考我在另一个类(场景.swift)中的视图控制器 - 所有变量都变为 null?斯威夫特 3.

Question

我正在尝试从我的 Scene.swift 类中的视图控制器调用一个方法 - 我能够做到。当我单击在我的视图控制器中设置的 SKLabel 节点时调用 touchesBegin 方法后，将调用该方法。

问题是，当我单击 SKLabelNode 时，控制权会传递给 Scene.swift 类，并且在 touchesBegin 方法中，调用了我要调用的方法，因此控件被传递回视图控制器，当我回到这里时，似乎我的所有变量都设置为 nil，就好像它是控制器的一个完全不同的实例一样？

当我尝试在 ArViewController 中设置标签的文本属性时，在 checkIfValidTime 方法中发生错误。 - 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同一实例，以便在 Scene.Swift 中声明变量时不会重置变量？ 或者有没有办法在视图控制器中实现touchesStarted方法，这样我就不必实例化ARViewController？

我将不胜感激有关此事的任何帮助，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。

我试图将代码限制为解释此问题所需的代码。 任何问题都只是问。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.")
}
}    

场景.斯威夫特：

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。(查看更新的编辑答案：强烈推荐)

ARViewController：在类外部创建实例

weak var arViewControllerInstance = ARViewController()

确保在ARView控制器类中初始化：

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

现在，您可以使用以下命令调用 Scene.Swift：

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

已编辑：强烈推荐

以上方法简单，但强烈建议不要作为最佳实践。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 类中添加上述委托，如下所示。

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

在 Scene 类中创建一个委托变量，如下所示 (Scene.swift)

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

一旦你首先实施。现在，您已经声明了ARViewController中的delegateARVC变量，如下面的代码所示。(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 Scene 类知道它与ARViewController的关系引用，方法是使用ScenceArViewControllerDelegate调用doPost的方法。

您可以从 Scene 类中调用AARViewController的doPost方法，如下所示。

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

您可以根据需要申请。谢谢。

Answer 2

@Liam 有"所有权链"。 "拥有"意味着承担保持物体生命的责任。示例图书馆、阅读器和书籍。书有图书馆的印章，所以它有参考，但绝对书不拥有图书馆。读者也一样。但图书馆和读者都声称拥有这本书的所有权。如果没有人拿书去读，声明所有权)，图书馆被摧毁——他们的书也被摧毁。

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strong。

通常，查看由应用委托或其他视图控制器(手动或使用情节提要)实例化的控制器。视图控制器可以使用其他任何人，并且可以了解视图控制器，但不"拥有"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。

总结一下：

1：将场景中的视图控制器声明为弱控制器：

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

2：为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：还有额外的修饰符"无主"。但它是更先进的技术，可能会导致问题和崩溃。我建议你让自己熟悉weak.习惯guard保留周期，然后继续。