已将数据保存在JSON文件中，但无法检索以前的数据，只能检索新条目

Question

我在第一个VC上的json文件上保存数据，同时加载数据，并在切换选项卡时显示。当我杀死应用程序或再次运行应用程序时，向json文件中添加新数据，只有那些新数据在json文件上，以前的数据不见了(删除而不手动删除(，无法加载。如何保存文件，以便下次运行程序时它只附加到以前的数据？

class ViewController: UIViewController {
var game : Game?
var weekLeague : [[Game]]? = []
override func viewDidLoad() {
super.viewDidLoad()
creation()
}
@IBAction func endWLButton(_ sender: UIButton) {
if games != nil {
weekLeague?.append(games!)
}
save()
}
func save(){
guard let documentDirectoryUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first else { return }
let fileUrl = documentDirectoryUrl.appendingPathComponent("ArrayOfArray.json")
print(fileUrl)
let json = try? JSONEncoder().encode(weekLeague)
do {
try json?.write(to: fileUrl)
print(json!)
print(weekLeague)
print("JSON data was written to teh file successfully!")
}catch{
print(error)
}
}
func ShouldSendGame(game: Game) {
self.game = game
games?.append(game)
}
func creation(){
let documentsDirectoryPathString = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).first!
let documentsDirectoryPath = NSURL(string: documentsDirectoryPathString)!
let jsonFilePath = documentsDirectoryPath.appendingPathComponent("ArrayOfArray.json")
let fileManager = FileManager.default
var isDirectory: ObjCBool = false
// creating a .json file in the Documents folder
if !fileManager.fileExists(atPath: jsonFilePath!.path, isDirectory: &isDirectory) {
let created = fileManager.createFile(atPath: jsonFilePath!.path, contents: nil, attributes: nil)
if created {
print("File created ")
} else {
print("Couldn't create file for some reason")
}
} else {
print("File already exists")
}
}

}

class AllLeagueController : UITableViewController {
var arrayOfArrayGamesCopy : [[Game]] = []
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
DispatchQueue.global().async {
self.loadData()
DispatchQueue.main.async {
self.tableView.reloadData()
}
}
}

func loadData() {
guard let documentsDirectoryUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first else { return }
let fileUrl = documentsDirectoryUrl.appendingPathComponent("ArrayOfArray.json")
do{
let data = try Data(contentsOf:fileUrl)
let decoder = JSONDecoder()
let jsonData = try decoder.decode([[Game]].self, from: data)
arrayOfArrayGamesCopy = jsonData
print("Succes")
print(jsonData.count)
} catch{
print(error)
}
}
}

Answer 1

保存之前需要在此处加载数据。。。此外，您还需要有单独的类来保存和加载数据。。dot在控制器中执行此操作。。这违背了单一责任原则。。。您的加载功能应返回[游戏]数组，保存数据应返回成功或失败

@IBAction func endWLButton(_ sender: UIButton) {
//load and set data in games from file ...then append current data and save to file 
if games != nil {
weekLeague?.append(games!)
}
save()
}