在 swift 2 中通过 segue 传递数据

Question

大家好，我的代码需要一些帮助，请查看图片以了解我看到的内容，我在 Swift 中制作了一个小费计算器项目，它必须有一个设置视图，我可以在其中选择默认小费率，我有一些错误，我必须尽快解决。我将非常感谢有人更正我的代码并对其进行测试。 图 1 (MainViewController) 图 2 (MainStoryBoard) 以下是两个 ViewController 的代码，我没有发布 Settings View Controller 的图像，因为网站不允许我发布两个以上的链接，直到我获得更多声誉。

import UIKit

class ViewController: UIViewController, SettingDelegate {
    // 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"
        TipPercentageLabel.text =  "20.0%"
        numberOfPersonLabel.text = "1"
        self.amountTextField.becomeFirstResponder()
    }

    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 = newValue
            refreshCalculation()
                }
            }

    }

下面是SettingsViewController的代码

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

    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 tipRates = [0.05, 0.10, 0.15, 0.20, 0.25, 0.30]
        let tipRate = tipRates[tipControl.selectedSegmentIndex]

        delegate?.tipPercentageChanged(tipRate)

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

    }

Answer 1

您必须将您的委托函数添加到您的 ViewController 类中，因为您的委托函数不是可选的。

将此添加到您的 ViewController 类中：

func tipPercentageChanged(newValue : Double) {
    //your code
}

Answer 2

首先，您还没有在 ViewController 类中实现 tipPercentageChanged 方法。由于 tipPercentageChanged 是 SettingDelegate 协议的必需方法，因此您必须实现它以符合协议。

第二，在prepareForSegue

        SettingsViewController.delegate = newValue

应该是

        SettingsViewController.delegate = self

既然是 SettingsViewController 的委托，那就是 ViewController。

所以你在 ViewController 中更新的代码应该是

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if let SettingsViewController = segue.destinationViewController as?SettingsViewController {
        SettingsViewController.delegate = self
        refreshCalculation()
    }
}

func tipPercentageChanged(newValue: Double) {

    // What you want to do, when Percentage is changed
    // Update tipSlider
    tipSlider.value = Float(newValue)
}

Answer 3

试试这个：

将您的 prepareForSegue 函数替换为：

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if let SettingsViewController = segue.destinationViewController as?SettingsViewController {
    SettingsViewController.delegate = self
    refreshCalculation()
}
}

并添加tipPercentageChanged函数

func tipPercentageChanged(newValue: Double) {
     TipPercentageLabel.text =  "\(newValue)%" //reset label value
     tipSlider.value = newValue //reset slider value too
}

希望对你有帮助！