Xcode 跳过 if else 语句

Question

我的 if else 语句检查某些文本字段是否为空，如果是则弹出警报。然而，xcode 即使经历了一切，也会转移到其他功能。

有一个 if 语句检查分段控件的值并相应地检查一些文本字段。

@IBAction func calc(_ sender: Any) {
    
    // Check if dilution text field is empty
    let dilutiontext = self.dilution.text
    if (dilutiontext?.isEmpty ?? true) {
        Alert.showAlert(on: self, with: "Empty Fields", message: "Dilution field is empty")
    }
    if choose.selectedSegmentIndex == 0 {
        
        if (self.number1.text?.isEmpty) ?? true || self.number2.text?.isEmpty ?? true || self.number3.text?.isEmpty ?? true || self.number4.text?.isEmpty ?? true {
            Alert.showAlert(on: self, with: "Empty Fields", message: "Number 1-4 fields should not be empty")
        } else {
            performSegue(withIdentifier: "turner", sender: self)
        }
    } else {
        if (self.number1.text?.isEmpty) ?? true || self.number2.text?.isEmpty ?? true || self.number3.text?.isEmpty ?? true || self.number4.text?.isEmpty ?? true || self.number5.text?.isEmpty ?? true || self.number6.text?.isEmpty ?? true || self.number7.text?.isEmpty ?? true || self.number8.text?.isEmpty ?? true {
            Alert.showAlert(on: self, with: "Empty Fields", message: "Number 1-8 fields should not be empty")
        } else {
            performSegue(withIdentifier: "turner", sender: self)
        }
    }
    
}

我有另一个控制警报的文件 alert.swift：

import Foundation
import UIKit

struct Alert {
    public static func showAlert(on vc: UIViewController, with title: String, message: String) {
        let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
        alert.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
        vc.present(alert, animated: true)
    }
}

编辑：

以前的 self.dilution.text?.isEmpty 现在让稀释文本 = self.dilution.text 和稀释文本?isEmpty

我注释掉了准备转场功能，令人惊讶的是，警报开始起作用了。我仍然需要该功能并且警报仍然有效。这是函数：

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    
    var vc = segue.destination as! SecondViewController
    
    if choose.selectedSegmentIndex == 0 {
        vc.n1 = Int(number1.text!)!
        vc.n2 = Int(number2.text!)!
        vc.n3 = Int(number3.text!)!
        vc.n4 = Int(number4.text!)!
        vc.dil = Int(dilution.text!)!
        vc.cn = Int(choose.selectedSegmentIndex)

    } else {
        vc.n1 = Int(number1.text!)!
        vc.n2 = Int(number2.text!)!
        vc.n3 = Int(number3.text!)!
        vc.n4 = Int(number4.text!)!
        vc.n5 = Int(number5.text!)!
        vc.n6 = Int(number6.text!)!
        vc.n7 = Int(number7.text!)!
        vc.n8 = Int(number8.text!)!
        vc.cn = Int(choose.selectedSegmentIndex)
        vc.dil = Int(dilution.text!)!
    }

}

当我运行它时，它不会显示警报（检查文本字段是否为空），而是继续执行 segue 函数并在展开可选值时显示 Unexpectedly found nil，这是预期的

Answer 1

显然“if”和“else if”条件都不成立。添加

let dilutiontext = self.dilution.text
let celltext = self.cell.text

然后设置断点并检查值。

Answer 2

如果 segue 函数中的 if 条件之一为真，则显然会跳过警报。因此，如果有什么东西最初会使这些陈述为假，然后在通过警报后它会使它们成为真的，那么问题就会得到解决。

因此，我为 segue func 中的 if 和 if else 语句分别制作了两个函数。

func option1() -> Bool {
    if (self.number1.text?.isEmpty) ?? true || self.number2.text?.isEmpty ?? true || self.number3.text?.isEmpty ?? true || self.number4.text?.isEmpty ?? true || self.dilution.text?.isEmpty ?? true || !(self.number5.text?.isEmpty ?? true) || !(self.number6.text?.isEmpty ?? true) || !(self.number7.text?.isEmpty ?? true) || !(self.number8.text?.isEmpty ?? true) {
        return false
    } else {
        return true
    }
}

func option2() -> Bool {
    if (self.number1.text?.isEmpty) ?? true || self.number2.text?.isEmpty ?? true || self.number3.text?.isEmpty ?? true || self.number4.text?.isEmpty ?? true || self.number5.text?.isEmpty ?? true || self.number6.text?.isEmpty ?? true || self.number7.text?.isEmpty ?? true || self.number8.text?.isEmpty ?? true || self.dilution.text?.isEmpty ?? true {
        return false
    } else {
        return true
    }
}

它检查所有条件是否为真，如果是则返回真，以便程序可以继续执行 segue 函数。

segue 将检查条件是否为真，如果不是，它将通过警报——因此使 option1() 或 option2() 返回 true——因此 segue func 中的 if 条件对于程序继续。

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    
    var vc = segue.destination as! SecondViewController

    if option1() == true {
        vc.n1 = Int(number1.text!)!
        vc.n2 = Int(number2.text!)!
        vc.n3 = Int(number3.text!)!
        vc.n4 = Int(number4.text!)!
        vc.dil = Int(dilution.text!)!
        vc.cn = Int(choose.selectedSegmentIndex)

    } else if option2() == true {
        vc.n1 = Int(number1.text!)!
        vc.n2 = Int(number2.text!)!
        vc.n3 = Int(number3.text!)!
        vc.n4 = Int(number4.text!)!
        vc.n5 = Int(number5.text!)!
        vc.n6 = Int(number6.text!)!
        vc.n7 = Int(number7.text!)!
        vc.n8 = Int(number8.text!)!
        vc.cn = Int(choose.selectedSegmentIndex)
        vc.dil = Int(dilution.text!)!
    }

}