iPhone 操作系统上的撤消重做基本上是如何工作的

iPhone 操作系统上的撤消/重做功能的工作原理

swift
import UIKit
class TextEditor {
    var text: String
    var history: [String]
    var currentIndex: Int
    
    init() {
        text = ""
        history = []
        currentIndex = -1
    }
    
    func insertText(_ newText: String) {
        text += newText
        saveToHistory()
    }
    
    func deleteText() {
        if !text.isEmpty {
            text.removeLast()
            saveToHistory()
        }
    }
    
    func undo() {
        if currentIndex > 0 {
            currentIndex -= 1
            text = history[currentIndex]
        }
    }
    
    func redo() {
        if currentIndex < history.count - 1 {
            currentIndex += 1
            text = history[currentIndex]
        }
    }
    
    private func saveToHistory() {
        currentIndex += 1
        if currentIndex < history.count {
            history.removeSubrange(currentIndex..        }
        history.append(text)
    }
}
// 使用示例
let editor = TextEditor()
editor.insertText("Hello")
editor.insertText(" World")
print(editor.text)  // 输出: Hello World
editor.undo()
print(editor.text)  // 输出: Hello
editor.redo()
print(editor.text)  // 输出: Hello World