如何以编程方式触发 UIContextMenuInteraction 上下文菜单？

Question

我在 UINavigationController 中的 UIViewController 中将 UIButton 设置为 rightBarButtonItem，并为其关联了一个 iOS13 上下文菜单。

长按按钮会按预期显示上下文菜单。

有没有一种方法也可以通过点击按钮来显示上下文菜单（例如，通过为 .touchUpInside 事件添加目标）？

button/barButtonItem设置如下：

let button = UIButton(type: .system)
button.setImage(UIImage(systemName: "plus"), for: .normal)

let barButton = UIBarButtonItem(customView: button)
self.navigationItem.rightBarButtonItem = barButton

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

上下文菜单定义如下：

extension ViewController: UIContextMenuInteractionDelegate {
    func contextMenuInteraction(_ interaction: UIContextMenuInteraction, configurationForMenuAtLocation location: CGPoint) -> UIContextMenuConfiguration? {
        return UIContextMenuConfiguration(identifier: nil, previewProvider: nil) { suggestedActions in
            let importAction = UIAction(title: "Import", image: UIImage(systemName: "folder")) { action in }
            let createAction = UIAction(title: "Create", image: UIImage(systemName: "square.and.pencil")) { action in }
            return UIMenu(title: "", children: [importAction, createAction])
        }
    }
}

Answer 1

根据设计，当出现适当的手势（用力触摸或长按）时，系统会自动显示上下文菜单。你不能手动显示它。

来自docs：

A context menu interaction object tracks Force Touch gestures on devices that support 3D Touch, and long-press gestures on devices that don't support it.

UIKit manages all menu-related interactions and reports the selected action, if any, back to your app.

更新:

尽管在 iOS14 中仍然无法手动显示上下文菜单，但现在可以将我们为上下文菜单创建的 UIMenu 显示为 pull-down menu. Check iOS 14.

Answer 2

iOS 14

iOS 14（第一个 Beta）现在支持所需的功能。使用以下代码点击 UIBarButtonItem 将立即显示菜单（同时避免调用 UIContextMenuInteraction 导致的背景模糊）：

override func viewDidLoad() {
    super.viewDidLoad()
    
    let importAction = UIAction(title: "Import", image: UIImage(systemName: "folder")) { action in }
    let createAction = UIAction(title: "Create", image: UIImage(systemName: "square.and.pencil")) { action in }
    
    let menuBarButton = UIBarButtonItem(
        title: "Add",
        image: UIImage(systemName:"plus"),
        primaryAction: nil,
        menu: UIMenu(title: "", children: [importAction, createAction])
    )
    
    self.navigationItem.rightBarButtonItem = menuBarButton
}

该功能是通过 而不是 提供 primaryAction。

您可以使用 UIButton 实现相同的效果。在这种情况下，您需要设置

button.showsMenuAsPrimaryAction = true

UIButton 的完整代码如下所示：

override func viewDidLoad() {
    super.viewDidLoad()
   
    let button = UIButton(type: .system)
    button.setImage(UIImage(systemName: "plus"), for: .normal)
    button.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(button)
    
    NSLayoutConstraint.activate([
        button.centerXAnchor.constraint(equalTo: view.centerXAnchor),
        button.centerYAnchor.constraint(equalTo: view.centerYAnchor)
    ])
    
    let importAction = UIAction(title: "Import", image: UIImage(systemName: "folder")) { action in }
    let createAction = UIAction(title: "Create", image: UIImage(systemName: "square.and.pencil")) { action in }
    
    let items = [importAction, createAction]
    
    button.menu = UIMenu(title: "Add", children: items)
    button.showsMenuAsPrimaryAction = true
}

Answer 3

使用私有 API 可以完成这项工作。

@objc
func buttonTapped() {
    // _presentMenuAtLocation:
    guard let interaction = imageView.interactions.first,
          let data = Data(base64Encoded: "X3ByZXNlbnRNZW51QXRMb2NhdGlvbjo="),
          let str = String(data: data, encoding: .utf8)
    else {
        return
    }
    let selector = NSSelectorFromString(str)
    guard interaction.responds(to: selector) else {
        return
    }
    interaction.perform(selector, with: CGPoint.zero)
}

如何以编程方式触发 UIContextMenuInteraction 上下文菜单？

How to trigger UIContextMenuInteraction context menu programmatically?

contextmenu

popupmenu

ios

ios13

ios14