ios - 不将文本字段识别为空

Question

我无法让代码识别 HourGoal 和 MinuteGoal 文本字段何时为空。它们永远不会出现为零值或空值，从而导致当我尝试解开这些值时程序崩溃。

import UIKit

class ReadingGoal: UIViewController {
    @IBOutlet weak var HourGoal: UITextField!
    @IBOutlet weak var MinuteGoal: UITextField!
    @IBOutlet weak var NextButton: UIButton!
    var mingoal = Int()
    var hrgoal = Int()
    var secondstoread:Int = 0
    var initialtime:Int = Int()

    @IBAction func HourEditingDidChange(_ sender: Any) {
        NextButton.isEnabled = true
    }

    @IBAction func MinuteEditingDidChange(_ sender: Any) {
        NextButton.isEnabled = true
    }

    func disable() {
        NextButton.isEnabled = false
    }

    @IBAction func NextButtonIsPressed(_ sender: Any) {
        print("GERALDINE IS AWESOME!!!!!")

        // ERROR
        if HourGoal.text?.isEmpty == false || MinuteGoal.text?.isEmpty == false {
            if HourGoal.text != nil && HourGoal.text?.isEmpty == false{
             //   self.hrgoal = Int(HourGoal.text!)!
                print("hr Value exists")
                print("\(HourGoal.text!)")
            }
            else {
                NextButton.isEnabled = false
            }
            if MinuteGoal.text != nil && MinuteGoal.text?.isEmpty == false{
              // self.mingoal = Int(MinuteGoal.text!)!
                print("min value exists")
                print("\(MinuteGoal.text!)")
            }
            else {
                NextButton.isEnabled = false
            }
            print("in ")
            // secondstoread = ((mingoal + (hrgoal*60))*60)
            secondstoread = 10

            if secondstoread > 0 {
                performSegue(withIdentifier: "Mr.Friar-DavisIsAGiantBallOfFloof", sender: self)
            }
            else {
                NextButton.isEnabled = false
            }
            //function saves text field info to core data
        }
    }

    //for the specific segue 'toBookInfo', certain information is passed through the segue
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        //making sure we are using correct segue
        if segue.identifier == "Mr.Friar-DavisIsAGiantBallOfFloof" {

                //selecting the destination controller
                let detailVC: TimerController = segue.destination as! TimerController

                //sending properties to destination view controller
                detailVC.seconds = secondstoread
            }
    else {
            // Error sender is not a cell or cell is not in collectionView.
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        initialtime = secondstoread
    }
}

Answer 1

这里不会教你术语，但所有变量都应该像这样以小写开头，甚至是 IBOutlets...

...好吧，我研究了你的代码一段时间:

不惜一切代价避免使用感叹号!!! -> 它经常崩溃的原因是因为你使用了!在任何地方，这种力量都会打开选项并完全破坏 swift 的美丽。

这条线如何与没有选项问题的编译器一起工作？

if HourGoal.text?.isEmpty == false || MinuteGoal.text?.isEmpty == false 

您正在以某种方式检查可选值，并且该值肯定为零，因此在代码行之前提供:

guard let hourGoalText = HourGoal.text, let minuteGoal = minuteGoal.text else { //handle code for empty textField
return }

这是检查选项的第一步...现在代码不会崩溃...但老实说没有调试

如果您使用guard let 或 if let 语句，则不会遇到崩溃问题