swift - if 语句返回的值不适用于 UiLabel

Question

我对 swift 和编程相当陌生，我正在尝试显示 if 语句中的值。这是我的 UiLabel 中的函数。我已经尝试了一些相同的变体，但它只返回“calculate.fuelTank”，它似乎永远不会触发我的 IF 语句的第二部分？

@IBOutlet weak var startingFuelDisplay: UILabel!  //not working yet
    func refreshUiopeningFuel() {

        if calculate.totalFuel <= Double(calculate.fuelTank) {

            print (Double(calculate.fuelTank)) // FuelTank

        } else {

            print (calculate.totalFuel) // TotalFuel
        }

我需要添加一个 bool 参数来触发“else”吗？我还尝试使用带有初始化字符串的“返回”函数，其中包含我试图提取的值，最后我需要它用于另一个显示器。

这是我的完整 View Controller 代码(我是新人，我确信它会更干净)

import UIKit

class ViewController: UIViewController {
    let calculate = Inputs ( raceLaps: 13, fuelRate: 3.7, fuelTank: 110, laptime: 85.456, tyreWear: 0.05 )

    @IBOutlet weak var rate: UITextField!
    @IBOutlet weak var laps: UITextField!
    @IBOutlet weak var tank: UITextField!
    @IBOutlet weak var tyreWear: UITextField!
    @IBOutlet weak var laptime: UITextField!

    @IBOutlet var cancelKeyboard: UITapGestureRecognizer!


    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        //Looks for single or multiple taps.
        let tap: UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: "dismissKeyboard")
        view.addGestureRecognizer(tap)
    }

    //Calls this function when the tap is recognized.
    func dismissKeyboard() {
        //Causes the view (or one of its embedded text fields) to resign the first responder status.
        view.endEditing(true)

            }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
        refreshUiFuel()
        refreshUiStops()
        refreshUiTyreLife()
        refreshUiTyreLifeLaps()
        refreshUiopeningFuel()
        refreshUiBoxOnLap ()


    }



    @IBAction func calculate(sender: UIButton) {
        if let rateVal = Double(rate.text!),
            tankVal = Int(tank.text!),
            lapVal = Int(laps.text!),
            wearVal = Double(tyreWear.text!),
        laptimeVal: Float = 85.456 {
                let fuelModel = Inputs(raceLaps: lapVal, fuelRate: rateVal, fuelTank: tankVal, laptime: laptimeVal, tyreWear: wearVal )
                totalFuelDisplay.text = ("\(Double(fuelModel.totalFuel))")
                totalStopsDisplay.text = ("\(Int(fuelModel.totalStops))")
                tyreLifeDisplay.text = ("\(Int(fuelModel.tyreChangesRaceDistanceTotal))")
                tyreLifeLapsDisplay.text = ("\(Int(fuelModel.tyreLife))")
                startingFuelDisplay.text = ("\(refreshUiopeningFuel())")
        }
        else {
            totalFuelDisplay.text = "missing value"
            totalStopsDisplay.text = "missing value"
            tyreLifeDisplay.text = "missing value"
            tyreLifeLapsDisplay.text = "missing value"
            startingFuelDisplay.text = "missing Value"
        }

                   }

    @IBOutlet weak var totalFuelDisplay: UILabel!
    func refreshUiFuel()->String {
        return totalFuelDisplay.text!
    }

    @IBOutlet weak var totalStopsDisplay: UILabel!
    func refreshUiStops()->String {
        return totalStopsDisplay.text!
    }

    @IBOutlet weak var tyreLifeDisplay: UILabel!
    func refreshUiTyreLife()->String {
        return tyreLifeDisplay.text!
    }
    @IBOutlet weak var tyreLifeLapsDisplay: UILabel!
    func refreshUiTyreLifeLaps()->String {
        return tyreLifeLapsDisplay.text!
    }
    @IBOutlet weak var pitOnLapDisplay: UILabel!
    func refreshUiBoxOnLap () {

    }



    @IBOutlet weak var startingFuelDisplay: UILabel!  //not working yet
        func refreshUiopeningFuel() ->Double {

            print(calculate.fuelTank)
            print(calculate.totalFuel)

            if calculate.totalFuel <= Double(calculate.fuelTank) {

                return Double(calculate.fuelTank) // FuelTank

            } else {

                return calculate.totalFuel // TotalFuel
            }


  }
} 

欢迎所有帮助

Answer 1

从现实世界的自然逻辑来看，您似乎只是颠倒了 if/else 逻辑。看起来，如果 totalFuel 小于油箱容量(if 子句)，在这种情况下您应该返回 totalFuel，并返回else 子句中的油箱容量。