为何点击ContextMenu选项后UIBarButtonItem的图标会变更？

这是因为你创建UIMenu时设置了.singleSelection选项——这是UIKit针对单选菜单的默认行为：当用户选中菜单里的某个UIAction时，系统会自动将该UIAction的图标替换为父控件UIBarButtonItem的当前图标，以此直观反馈用户的单选选择状态。

根据你的需求，有两种处理方式：

1. 移除单选选项（无需单选功能时） #

直接去掉UIMenu的.singleSelection选项，菜单就不会触发图标替换行为：

func makeUIMenu() -> UIMenu {
    guard let emptyFolder, let importFile, let importPhotoOrVideo else { return UIMenu() }
    return UIMenu(title: "Add",
                  image: .folder.applyingSymbolConfiguration(.symbolConfig),
                  options: [.displayInline], // 移除.singleSelection
           children: [importPhotoOrVideo, importFile, emptyFolder])
}

2. 保留单选但手动控制图标（需要单选功能时） #

如果要保留单选逻辑，但不想替换UIBarButtonItem的图标，可以手动管理UIAction的选中状态，并在每次操作后重置图标：

private init() {
    emptyFolder = UIAction(
        title: "Empty Folder",
        image: .folderBadgePlus.applyingSymbolConfiguration(.symbolConfig),
        identifier: nil,
        state: .off,
        handler: { action in
            // 取消其他选项的选中状态
            self.importFile?.state = .off
            self.importPhotoOrVideo?.state = .off
            // 切换当前选项状态
            action.state = .on
            // 重置UIBarButtonItem图标
            (self.delegate as? ViewController)?.fooItem.image = .folder.applyingSymbolConfiguration(.symbolConfig)
            self.delegate?.didTappedEmptyFolder()
        }
    )
    
    importFile = UIAction(
        title: "Import File",
        image: .squareAndArrowDown.applyingSymbolConfiguration(.symbolConfig),
        identifier: nil,
        state: .off,
        handler: { action in
            self.emptyFolder?.state = .off
            self.importPhotoOrVideo?.state = .off
            action.state = .on
            (self.delegate as? ViewController)?.fooItem.image = .folder.applyingSymbolConfiguration(.symbolConfig)
            self.delegate?.didTappedImportFile()
        }
    )
    
    importPhotoOrVideo = UIAction(
        title: "Import Photo & Video",
        image: .photo.applyingSymbolConfiguration(.symbolConfig),
        identifier: nil,
        state: .off,
        handler: { action in
            self.emptyFolder?.state = .off
            self.importFile?.state = .off
            action.state = .on
            (self.delegate as? ViewController)?.fooItem.image = .folder.applyingSymbolConfiguration(.symbolConfig)
            self.delegate?.didTappedImportFile()
        }
    )
}

// 移除UIMenu的.singleSelection选项
func makeUIMenu() -> UIMenu {
    guard let emptyFolder, let importFile, let importPhotoOrVideo else { return UIMenu() }
    return UIMenu(title: "Add",
                  image: .folder.applyingSymbolConfiguration(.symbolConfig),
                  options: [.displayInline],
           children: [importPhotoOrVideo, importFile, emptyFolder])
}

内容的提问来源于stack exchange，提问作者Ufuk Köşker