ios - iPadOS:防止不使用指针时触发UIContextMenuInteraction

UIMenu vs UIContextMenuInteraction vs UIPointerInteraction
我正在尝试以与“文件或页面”应用程序相同的方式设置UIContextMenuInteraction:

(长按)在空白处的任意位置显示黑色水平UIMenu

在空白区域中的任意位置单击鼠标指针(右键/控制)，显示上下文菜单

请参阅下面随附的GIF上的演示。

我可以设置UIContextMenuInteraction，并在其UIContextMenuInteractionDelegate中返回包含我要显示的项目的UIContextMenuConfiguration。

对于小的黑色UIMenu一样，我可以使用UILongPressGestureRecognizer并使用UIMenuController.shared.showMenu显示菜单。

但是，当长按视图时，我无法阻止UIContextMenuInteraction触发并显示UITargetedPreview，现在似乎已经有了通过UITouchType提供的信息来识别不同的UIContextMenuInteractionDelegate的方法。

如果没有UIContextMenuInteraction，我也找不到如何以编程方式显示上下文菜单。有没有办法做到这一点？

题

在Files.app中如何实现？

最佳答案

无法以编程方式触发上下文菜单，但是通过一些简单的簿记操作，您可以防止在不需要时显示该菜单(例如，当响应者上的触摸处于 Activity 状态时)。

要隐藏预览，只需在UIContextMenuConfiguration的初始化程序中从previewProvider返回nil即可。

这是一个以视图控制器的视图为目标的完整实现:

import UIKit

class ViewController: UIViewController {

    var touchesInSession = false

    override func viewDidLoad() {
        super.viewDidLoad()

        let interaction = UIContextMenuInteraction(delegate: self)
        view.addInteraction(interaction)

        let recognizer = UILongPressGestureRecognizer(target: self, action: #selector(longPressHandler))
        view.addGestureRecognizer(recognizer)
    }

    @objc func longPressHandler(recognizer: UILongPressGestureRecognizer) {
        guard recognizer.state == .began else { return }
        presentMenu(from: recognizer.location(in: view))
    }

    func presentMenu(from location: CGPoint) {
        view.becomeFirstResponder()
        let saveMenuItem = UIMenuItem(title: "New Folder", action: #selector(createFolder))
        let deleteMenuItem = UIMenuItem(title: "Get Info", action: #selector(getInfo))
        UIMenuController.shared.menuItems = [saveMenuItem, deleteMenuItem]
        UIMenuController.shared.showMenu(from: view, rect: .init(origin: location, size: .zero))
    }

    @objc func createFolder() {
        print("createFolder")
    }

    @objc func getInfo() {
        print("getInfo")
    }

    // MARK: UIResponder
    override var canBecomeFirstResponder: Bool { true }

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        super.touchesBegan(touches, with: event)
        touchesInSession = true
    }

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        super.touchesEnded(touches, with: event)
        touchesInSession = false
    }

    override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {
        super.touchesCancelled(touches, with: event)
        touchesInSession = false
    }
}

extension ViewController: UIContextMenuInteractionDelegate {
    func contextMenuInteraction(_ interaction: UIContextMenuInteraction, configurationForMenuAtLocation location: CGPoint) -> UIContextMenuConfiguration? {
        guard !touchesInSession else { return nil }
        let configuration = UIContextMenuConfiguration(identifier: "PointOnlyContextMenu" as NSCopying, previewProvider: { nil }, actionProvider: { suggestedActions in
            let newFolder = UIAction(title: "New Folder", image: UIImage(systemName: "folder.badge.plus")) { [weak self] _ in
                self?.createFolder()
            }
            let info = UIAction(title: "Get Info", image: UIImage(systemName: "info.circle")) { [weak self] _ in
                self?.getInfo()
            }
            return UIMenu(title: "", children: [newFolder, info])
        })
        return configuration
    }
}