在快速MVC中保存tableview数据

Question

I have this code. I'm developing my app without storyboard:

SecondController.swift

class SecondController: UIViewController {

var items: [String] = ["DATA 1", "DATA 2", "DATA 3"]
let tableView: UITableView  =   UITableView()

init(){
    super.init(nibName: nil, bundle: nil)
    self.view = SecondView()
    self.view.backgroundColor=UIColor.green

    tableView.frame         =   CGRect(0, 50, 320, 200);
    tableView.delegate      =   self
    tableView.dataSource    =   self
    tableView.register(UITableViewCell.self, forCellReuseIdentifier: "cell")
    self.view.addSubview(tableView)
}

override var prefersStatusBarHidden: Bool {
    return true
}

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view.
}

func onClickListener(object : UIButton!) {
    self.navigationController!.popViewController(animated: false)
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}
override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
}

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
}}
extension SecondController: UITableViewDataSource, UITableViewDelegate {

func tableView(_ tableView:UITableView, numberOfRowsInSection section:Int) -> Int {
    return self.items.count
}

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    print("You selected cell #\(indexPath.row)!")
    items.append("NEW DATA")
    print(items.count)
    self.tableView.reloadData()
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell:UITableViewCell = tableView.dequeueReusableCell(withIdentifier: "cell")!
    cell.textLabel?.text = self.items[indexPath.row]
    return cell
}}

And SecondView.swift

class SecondView: UIView {
var btnImage = UIButton(image: "resume")

override init(frame: CGRect){
    super.init(frame: screenSize)
    self.backgroundColor = UIColor.black

    // Btn
    self.btnImage.translatesAutoresizingMaskIntoConstraints = false
    addSubview(self.btnImage)
    self.btnImage.alignLeftOfViewVoid(padding: 1)
    self.btnImage.addTarget(self.parentViewController, action: #selector (SecondController.onClickListener(object:)), for: .touchUpInside)

}


required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

deinit{
    self.removeFromSuperview()
}}

The table works perfectly, but when I press the button the app returns to FirstView and FirstController, and when I want return to SecondView and SecondController, I lose the new data items.

Where can I put the array data if I don't want lose them? Can I separate the TableView in another file?

Thank you

Answer 1

You said you go back to FirstController , so your SecondController gets destroyed from memory along with items array. If you want to have them accessible across the app, you should create a Model class (according to MVC pattern that you mentioned yourself in your question title).

class DataStorage {
    static let shared = DataStorage()
    var items: [String] = ["DATA 1", "DATA 2", "DATA 3"]
}

Now you can access this data from your SecondController like this:

func tableView(_ tableView:UITableView, numberOfRowsInSection section:Int) -> Int {
    return DataStorage.shared.items.count
}

This is, of course, rough implementation, and you will most likely need to implement a set of methods in DataStorage class to modify (create, update, delete) your items .

UPD : This way lets you only store data in memory until app is terminated. In order to persist it, you need to store it on disk using CoreData , SQLite , Property Lists etc, as described in article suggested by @f_qi. Anyway, you should have separated Model file like DataStorage to manage this logic.

Answer 2

You did not implement any data persistent method.
Take a look at this link, it shows a couple ways to persist your data.
It's form 2015, so you need to understand it and apply swift 3.1 accordingly.