问(自行回答)Swift数组在函数numberofRows中返回0计数(在tableView中，但在其他任何地方它都会返回正确数量的array.count

EN

import Cocoa

class ViewController: NSViewController, NSTableViewDataSource, NSTableViewDelegate {

    var coursesDict = [String: Course]()
    var coursesArray = [Course]()

    @IBAction func refreshTable(_ sender: Any) {
        table.reloadData()
    }
    @IBOutlet weak var table: NSTableView!

    func numberOfSectionsInTableView(tableView: NSTableView) -> Int {
        return 1
    }

    func numberOfRows(in tableView: NSTableView) -> Int {

        let numOfRows = coursesArray.count
        print(numOfRows)

        return numOfRows

    }

    func tableView(_ tableView: NSTableView, objectValueFor tableColumn: NSTableColumn?, row: Int) -> Any? {
        return coursesArray[row]
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        if let data = UserDefaults.standard.data(forKey: "courses"),
            let savedCourses = NSKeyedUnarchiver.unarchiveObject(with: data) as? [String: Course] {
            self.coursesDict = savedCourses
            loadDataFromURL()

            self.coursesArray = Array(coursesDict.values)
            print(coursesDict.count, " appLaunch")
        } else {
            print("There is an issue")
        }
    }

        override var representedObject: Any? {
        didSet {
        // Update the view, if already loaded.
        }
    }

    override func viewDidDisappear() {
        let encodedData = NSKeyedArchiver.archivedData(withRootObject: coursesDict)
        UserDefaults.standard.set(encodedData, forKey: "courses")
        print(coursesDict.count, "viewUnload")
    }

    func loadDataFromURL() {
        // Fetch URL
        let url = URL(string: "https://www.apple.com/nl/today/static/data/hub/1101000001001110001.json")!

        // Load Data
        let data = try! Data(contentsOf: url)

        // Deserialize JSON
        let json = try! JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [String: AnyObject]

        let coursesJSON = json?["courses"] as? [AnyObject]

        for object in coursesJSON! {
            let id = object["id"] as! String
            if coursesDict[id] == nil {
                let name = object["shortName"] as! String
                let program = object["programName"] as! String
                let shortDescription = object["shortDesc"] as! String
                let mediumDescription = object["mediumDesc"] as! String
                let longDescription = object["longDesc"] as! String
                let imageURL = object["image"] as! String

                let tempCourse = Course(id: id, name: name, program: program, shortDescription: shortDescription, mediumDescription: mediumDescription, longDescription: longDescription, imageURL: imageURL)

                coursesDict[id] = tempCourse
            }
        }
        print(coursesDict.count, "loadURL")
    }

}