在swift2

Question

这是一个Tip Calculator应用程序的代码，它有一个设置视图，我在其中选择默认提示率，问题是当我启动应用程序并开始在文本字段中输入数量时，tipPercentageLabel设置为＆ ＃34; 0.0％＆＃34;直到我使用滑块选择一个百分比，当我进入设置视图时，我将tipRate设置为百分比，例如30％，我回到主视图控制器，就像我启动应用程序时一样。如果你想在这里测试它是下载项目的链接[链接] https://www.dropbox.com/s/rb8zwkz51ipinp0/Tip%20Calc%20Pro.xcodeproj.zip?dl=0 以下是Codepath大学为此项目提供的指示，该项目决定谁进入他们的诅咒http://courses.codepath.com/snippets/intro_to_ios/prework.md

查看控制器

import UIKit
class ViewController: UIViewController, SettingsDelegate {
// Inputs
@IBOutlet weak var amountTextField: UITextField!
//Labels
@IBOutlet weak var TipPercentageLabel: UILabel!
@IBOutlet weak var numberOfPersonLabel: UILabel!
@IBOutlet weak var tipAmountLabel: UILabel!
@IBOutlet weak var totalBillLabel: UILabel!
@IBOutlet weak var billPerPersonLabel: UILabel!
//Slider & Stepper
@IBOutlet weak var tipSlider: UISlider!
@IBOutlet weak var personsStepper: UIStepper!
//Variables
var tipPercentage : Double = NSUserDefaults.standardUserDefaults().doubleForKey("DefaultTipRate") ?? 0.20
var numberOfPerson:Int = 1
let numberFormatter:NSNumberFormatter = NSNumberFormatter()


override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    tipAmountLabel.text = "$0.00"
    totalBillLabel.text = "Bill Total"
    billPerPersonLabel.text = "$0.00"
    numberOfPersonLabel.text = "1"
    self.amountTextField.becomeFirstResponder()
}
override func viewWillAppear(animated: Bool) {
    print("DefaultTipRate")
    var tipPercentage : Double = NSUserDefaults.standardUserDefaults().doubleForKey("DefaultTipRate")
    TipPercentageLabel.text = self.numberFormatter.stringFromNumber(tipPercentage)
}


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


    tipSlider.minimumValue = 0
    tipSlider.maximumValue = 100
    tipSlider.value = 20
    tipSlider.addTarget(self, action: "sliderTipChanged:", forControlEvents: .ValueChanged)

    personsStepper.minimumValue = 1
    personsStepper.maximumValue = 30
    personsStepper.value = 1
    personsStepper.addTarget(self, action: "sliderPersonChanged:", forControlEvents: .ValueChanged)

    amountTextField.text = ""

    refreshCalculation()

}

@IBAction func OnEditingFieldBill(sender: AnyObject) {

    refreshCalculation()
}

func refreshCalculation() {

    numberFormatter.numberStyle = NSNumberFormatterStyle.DecimalStyle
    if let amount = numberFormatter.numberFromString(amountTextField.text!) as? Double {

        let tipAmount = amount * tipPercentage
        let totalBill = amount + tipAmount
        let billPerPerson = totalBill / Double(numberOfPerson)
        numberFormatter.numberStyle = NSNumberFormatterStyle.CurrencyStyle
        tipAmountLabel.text = numberFormatter.stringFromNumber(tipAmount)
        totalBillLabel.text = numberFormatter.stringFromNumber(totalBill)
        billPerPersonLabel.text = numberFormatter.stringFromNumber(billPerPerson)

    } else {

        tipAmountLabel.text = "-"
        totalBillLabel.text = "-"
        billPerPersonLabel.text = "-"
    }

    numberFormatter.numberStyle = NSNumberFormatterStyle.PercentStyle
    numberFormatter.minimumFractionDigits = 1
    numberFormatter.maximumFractionDigits = 1
    TipPercentageLabel.text = self.numberFormatter.stringFromNumber(tipPercentage)

   numberOfPersonLabel.text = "\(numberOfPerson)"

} 

@IBAction func sliderTipChanged(sender: UISlider) {

    tipPercentage = Double(round(tipSlider.value)) / 100
    refreshCalculation()
}


@IBAction func StepperPersonChanged(sender: UIStepper) {
    numberOfPerson = Int(round(personsStepper.value))
    refreshCalculation()
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if let SettingsViewController = segue.destinationViewController as? SettingsViewController {
        SettingsViewController.delegate = self
        refreshCalculation()
            }
        }
func tipPercentageChanged(newValue: Double) {
    TipPercentageLabel.text = "\(newValue)%"
    tipPercentage = newValue
    refreshCalculation()
}
}

设置视图控制器

import UIKit
protocol SettingsDelegate{
func tipPercentageChanged(newValue : Double)
}
class SettingsViewController: UIViewController {
@IBOutlet weak var tipControl: UISegmentedControl!
var tipRates: Double?
var destName : String!
var delegate :SettingsDelegate?

override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}
@IBAction func DefaultRate(sender: AnyObject) {
    var tipRate = [5, 10, 15, 20, 25, 30]
    tipRates = Double(tipRate[tipControl.selectedSegmentIndex])
    delegate?.tipPercentageChanged(tipRates!)


    NSUserDefaults.standardUserDefaults().setDouble(tipRates!, forKey: "DefaultTipRate")
    NSUserDefaults.standardUserDefaults().synchronize()

}