从标签（IOS）

Question

从Label。复制按钮。

我有计算器的代码，但我无法弄清楚如何做到这一点，当我点击按钮时，复制带有标签的数字。 或者我怎样才能做到这一点，当我长按它似乎复制：

“

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var displayResultLabel: UILabel!
    var stillTyping = false
    var dotIsPlaced = false
    var firstOperand: Double = 0
    var secondOperand: Double = 0
    var operationSign: String = ""

    var currentInput: Double {
        get {
            return Double (displayResultLabel.text!)!
        }
        set {
            let value = "\(newValue)"
            let ValueArray = (value.components(separatedBy:"."))
            if ValueArray[1] == "0" {
                displayResultLabel.text = "\(ValueArray[0])"
            } else {
                displayResultLabel.text = "\(newValue)"
            }
            stillTyping = false
        }
    }

    @IBAction func numberPressed(_ sender: UIButton) {
        let number = sender.currentTitle!

        if stillTyping {
            if (displayResultLabel.text?.characters.count)! < 20 {
                displayResultLabel.text = displayResultLabel.text! + number
            }
        } else {
            displayResultLabel.text = number
            stillTyping = true
        }
    }

    @IBAction func twoOperandsSignPressed(sender: UIButton) {
        operationSign = sender.currentTitle!
        firstOperand = currentInput
        stillTyping = false
        dotIsPlaced = false
    }

    func operateWithTwoOperands(operation: (Double, Double) -> Double) {
        currentInput = operation(firstOperand, secondOperand)
        stillTyping = false
    }

    @IBAction func equalitySignPressed(sender: UIButton) {
        if stillTyping {
            secondOperand = currentInput
        }

        dotIsPlaced = false

        switch operationSign {
        case "+":
            operateWithTwoOperands{$0 + $1}
        case "-":
            operateWithTwoOperands{$0 - $1}
        case "×":
            operateWithTwoOperands{$0 * $1}
        case "÷":
            operateWithTwoOperands{$0 / $1}
        default: break
        }
    }

    @IBAction func dotButtonPressed(_ sender: UIButton) {
        if stillTyping && !dotIsPlaced {
            displayResultLabel.text = displayResultLabel.text! + "."
            dotIsPlaced = true
        } else if !stillTyping && !dotIsPlaced {
            displayResultLabel.text = "0."
        }
    }
}

Answer 1

我会回答你的两个问题。

第一个问题：如何按下可以复制UILabel上显示的文字的按钮？

<强>答案：

@IBAction func yourButtonAction(_ sender: UIButton) {
    UIPasteboard.general.string = yourLabel.text
}

第二个问题：如何长按显示“复制”操作的UILabel？

<强>答案：

要使UILabel可复制，我们需要创建一个自定义类，它是UILabel的子类。暂时叫CopyableLabel：

import UIKit

class CopyableLabel: UILabel {

    override var canBecomeFirstResponder: Bool { return true }

    override init(frame: CGRect) {
        super.init(frame: frame)
        sharedInit()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        sharedInit()
    }

    override func copy(_ sender: Any?) {
        UIPasteboard.general.string = text
        UIMenuController.shared.setMenuVisible(false, animated: true)
    }

    override func canPerformAction(_ action: Selector, withSender sender: Any?) -> Bool {
        return action == #selector(copy(_:))
    }
}

// MARK: Actions methods
extension CopyableLabel {

    func longPressGestureActionHandler(_ sender: UILongPressGestureRecognizer) {
        becomeFirstResponder()

        let menu = UIMenuController.shared

        if !menu.isMenuVisible {
            menu.setTargetRect(bounds, in: self)
            menu.setMenuVisible(true, animated: true)
        }
    }
}

// MARK: Helper methods
extension CopyableLabel {

    func sharedInit() {
        isUserInteractionEnabled = true
        addGestureRecognizer(UILongPressGestureRecognizer(target: self, action: #selector(longPressGestureActionHandler(_:))))
    }
}

并使用CopyableLabel代替纯UILabel：

let yourLabel: CopyableLabel = CopyableLabel()

如果使用Interface Builder，请确保已定义Label的基类：

Answer 2

您可以使用UIPasteboard实施复制和粘贴。您可以在其属性string上读取和写入值，例如：

displayResultLabel.text = UIPasteboard.general.string

将粘贴板中的当前值粘贴到您的标签中，然后

UIPasteboard.general.string = displayResultLabel.text

将值从标签复制到粘贴板。