UISegmentedControl 动作中的 UIButton

Question

我正在继续我的计算程序，以提高我的 Swift 代码技能。 Right now I have a problem: I want that an UISegmentedControl select the operator of my operations (+, - ecc..) and when one is selected a UIButton func calculate the values based on the decision of the UISegmentedControl.

这是代码，但不起作用。

谢谢， 马特奥

import UIKit

class ViewController: UIViewController {


@IBOutlet weak var firstNumber: UITextField!
@IBOutlet weak var secondNumber: UITextField!
@IBOutlet weak var resultButton: UIButton!
@IBOutlet weak var resultNumber: UILabel!
@IBOutlet weak var operatorSelector: UISegmentedControl!

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.


}

override func didReceiveMemoryWarning() {

    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


@IBAction func operatorSelectorChanged(_ sender: UISegmentedControl) {
    switch operatorSelector.selectedSegmentIndex {
    case 0:
        @IBAction func resultFunction(_ sender: AnyObject) {
            if let firstNumberConv :Int = Int(firstNumber.text!), let secondNumberConv :Int = Int(secondNumber.text!) {
                let result = firstNumberConv + secondNumberConv
                resultNumber.text = "\(result)"
            } else { resultNumber.text = "Inserire solo valori numerici"}
        }


    case 1:
        @IBAction func resultFunction(_ sender: AnyObject) {
            if let firstNumberConv :Int = Int(firstNumber.text!), let secondNumberConv :Int = Int(secondNumber.text!) {
                let result = firstNumberConv - secondNumberConv
                resultNumber.text = "\(result)"
            } else { resultNumber.text = "Inserire solo valori numerici"}
        }

    default:
        break;

    }

}



}

Answer 1

尝试删除开关盒中带有@IBAction func ... 的行。

我认为你的@IBAction func operatorSelectorChanged 应该是这样的：

@IBAction func operatorSelectorChanged(_ sender: UISegmentedControl) {
    switch operatorSelector.selectedSegmentIndex {
    case 0:
        if let firstNumberConv = Int(firstNumber.text!), let secondNumberConv = Int(secondNumber.text!) {
            let result = firstNumberConv + secondNumberConv
            resultNumber.text = "\(result)"
        } else { resultNumber.text = "Inserire solo valori numerici"}


    case 1:
        if let firstNumberConv = Int(firstNumber.text!), let secondNumberConv = Int(secondNumber.text!) {
            let result = firstNumberConv - secondNumberConv
            resultNumber.text = "\(result)"
        } else { resultNumber.text = "Inserire solo valori numerici"}

    default:
        break;

    }

}

Answer 2

您的问题的一个可能解决方案是定义一个 IBAction 来计算两个数字相加/相减的结果

@IBAction func calculate(_ sender: AnyObject) {
    if let a = Int(firstNumber.text!), let b = IntsecondNumber.text!) {
        switch operatorSelector.selectedSegmentIndex {
        case 0:
            resultNumber.text = "\(a+b)"
        case 1:
            resultNumber.text = "\(a-b)"
        default:
            print("❗️unknown operator selected")
        }
    }
}

然后您可以将此操作绑定到从您的用户界面发送的事件：例如，您的文本字段（firstNumber 和 secondNumber）的Editing Changed 事件和您的分段控件（operatorSelector）的Value Changed

我创建了一个示例项目来说明这一点：https://github.com/dev1an/calculator

---

如何将多个事件绑定到一个 IBAction

在代码中写下 IBAction（就像我上面写的计算操作）。转到您的故事板并打开辅助编辑器（AltCmdEnter）。在界面构建器中选择一个 UI 元素（如文本字段）。打开 Connections Inspector (AltCmd6) 并从已发送事件（例如 Editing Changed）旁边的圆圈拖动到您的 IBAction 代码.