swift - 如何在 Swift 中将 NSUserDefault 与 PickerView 一起使用？

Question

我制作了一些使用 PickerView 更改的 Labels。但是当我更改 Label 并且如果我再次运行我的应用程序时，它不会保存到选定的一个。所以我必须使用 NSUserDefault 但我不知道如何以正确的方式使用它。

这是我的代码:

var selectedFood = 0

class ViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource {

@IBOutlet var foodLabel: UILabel!
@IBOutlet var labelTwo: UILabel!
@IBOutlet var labelThree: UILabel!

@IBOutlet weak var foodPicker: UIPickerView!

var food = ["Bread", "Pizza", "Pasta", "Hot Dog", "Burger"]

@IBAction func submitLanguageButton(sender: AnyObject) {
    if (selectedFood == 0) {
       foodLabel.text = "Bread"
       labelTwo.text = "Bread is a staple food prepared from a dough of flour and water..."
       labelThree.text = "Bread is one of the oldest prepared foods..." // I used random information just as sample         
    }
    else if (selectedFood == 1) {
       foodLabel.text = "Pizza"
       labelTwo.text = "Here will be more informations about Pizza"
       labelThree.text = "A fact about Pizza"   // I used random information just as sample              
    }
    else if (selectedFood == 2) {
       foodLabel.text = "Pasta"
       labelTwo.text = "Here will be more informations about Pasta"
       labelThree.text = "A fact about Pasta"    // I used random information just as sample                 
    }
    else if (selectedFood == 3) {
       foodLabel.text = "Hot Dog"
       labelTwo.text = "Here will be more informations about Hot Dog"
       labelThree.text = "A fact about Hot Dog"  // I used random information just as sample                   
    }
    else if (selectedFood == 4) {
       foodLabel.text = "Burger"
       labelTwo.text = "Here will be more informations about Burger"
       labelThree.text = "A fact about Burger" // I used random information just as sample         
    }
}

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

    foodPicker.delegate = self
    foodPicker.dataSource = self


    if (selectedFood == 0) {
       foodLabel.text = "Bread"
       labelTwo.text = "Bread is a staple food prepared from a dough of flour and water..."
       labelThree.text = "Bread is one of the oldest prepared foods..." // I used random information just as sample         
    }
    else if (selectedFood == 1) {
       foodLabel.text = "Pizza"
       labelTwo.text = "Here will be more informations about Pizza"
       labelThree.text = "A fact about Pizza"   // I used random information just as sample              
    }
    else if (selectedFood == 2) {
       foodLabel.text = "Pasta"
       labelTwo.text = "Here will be more informations about Pasta"
       labelThree.text = "A fact about Pasta"    // I used random information just as sample                 
    }
    else if (selectedFood == 3) {
       foodLabel.text = "Hot Dog"
       labelTwo.text = "Here will be more informations about Hot Dog"
       labelThree.text = "A fact about Hot Dog"  // I used random information just as sample                   
    }
    else if (selectedFood == 4) {
       foodLabel.text = "Burger"
       labelTwo.text = "Here will be more informations about Burger"
       labelThree.text = "A fact about Burger" // I used random information just as sample         
    }
}


func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    return food[row]
}

func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    return food.count
}

public func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
    return 1
}

func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {

    selectedFood = row
}

}

因此，当我选择Pizza 时，每当我运行我的应用程序时，我都希望它是Pizza，如果我选择另一个Pasta ，我想成为那个意大利面。你能帮帮我吗？

Answer 1

WBMDDrugManagerErrorCode 像这样保存选择:

func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    NSUserDefaults.standardUserDefaults().setInteger(row, forKey: "choosenFood")
    NSUserDefaults.standardUserDefaults().synchronize()
    self.setLabelsForChoice(row)
}

像这样检索选定的选择:

override func viewWillAppear() {
    super.viewWillAppear()
    if let previousSelection:Int = NSUserDefaults.standardUserDefaults().integerForKey("choosenFood") as? Int{
        self.setLabelsForChoice(previousSelection)
    }
}

创建一个与此类似的标签更新方法:

func setLabelsForChoice(_choice:Int){
    switch _choice{
        case 0:
            foodLabel.text = "Bread"
            labelTwo.text = "Bread is a staple food prepared from a dough of flour and water..."
            labelThree.text = "Bread is one of the oldest prepared foods..."
            break
        case 1:
            foodLabel.text = "Pizza"
            labelTwo.text = "Here will be more informations about Pizza"
            labelThree.text = "A fact about Pizza"
            break
        default:

            break
    }




}