是通过使用UIContextMenuInteraction实现的。UIContextMenuInteraction是iOS 13及更高版本引入的一个API,用于在用户长按视图时显示上下文菜单。
要将UIView显示为上下文菜单预览,需要执行以下步骤:
contextMenuInteraction(_:configurationForMenuAtLocation:)
:返回一个UIContextMenuConfiguration对象,用于配置上下文菜单的内容和行为。contextMenuInteraction(_:previewForHighlightingMenuWithConfiguration:)
:返回一个UIViewController对象,用于在用户高亮显示菜单项时显示预览。contextMenuInteraction(_:previewForDismissingMenuWithConfiguration:)
:返回一个UIViewController对象,用于在用户取消菜单时显示预览。contextMenuInteraction(_:willDisplayMenuForConfiguration:animator:)
:在菜单显示之前执行的操作。contextMenuInteraction(_:willEndForConfiguration:animator:)
:在菜单即将结束时执行的操作。contextMenuInteraction(_:willPerformPreviewActionForMenuWith:animator:)
:在用户选择菜单项时执行的操作。完整的代码示例如下:
import UIKit
class ViewController: UIViewController, UIContextMenuInteractionDelegate {
override func viewDidLoad() {
super.viewDidLoad()
// 创建一个UIView,并添加到视图层次结构中
let myView = UIView(frame: CGRect(x: 100, y: 100, width: 100, height: 100))
myView.backgroundColor = UIColor.red
view.addSubview(myView)
// 创建遵循UIContextMenuInteractionDelegate协议的对象
let contextMenuDelegate = self
// 创建UIContextMenuInteraction对象,并将其添加到UIView上
let interaction = UIContextMenuInteraction(delegate: contextMenuDelegate)
myView.addInteraction(interaction)
}
// 实现UIContextMenuInteractionDelegate协议的代理方法
func contextMenuInteraction(_ interaction: UIContextMenuInteraction, configurationForMenuAtLocation location: CGPoint) -> UIContextMenuConfiguration? {
// 返回一个UIContextMenuConfiguration对象,用于配置上下文菜单的内容和行为
return UIContextMenuConfiguration(identifier: nil, previewProvider: nil) { _ in
// 创建菜单项
let action1 = UIAction(title: "Action 1", image: UIImage(systemName: "star")) { _ in
// 执行菜单项的操作
print("Action 1 selected")
}
let action2 = UIAction(title: "Action 2", image: UIImage(systemName: "heart")) { _ in
// 执行菜单项的操作
print("Action 2 selected")
}
// 返回菜单的内容
return UIMenu(title: "Menu", children: [action1, action2])
}
}
func contextMenuInteraction(_ interaction: UIContextMenuInteraction, previewForHighlightingMenuWithConfiguration configuration: UIContextMenuConfiguration) -> UITargetedPreview? {
// 返回一个UIViewController对象,用于在用户高亮显示菜单项时显示预览
return nil
}
func contextMenuInteraction(_ interaction: UIContextMenuInteraction, previewForDismissingMenuWithConfiguration configuration: UIContextMenuConfiguration) -> UITargetedPreview? {
// 返回一个UIViewController对象,用于在用户取消菜单时显示预览
return nil
}
func contextMenuInteraction(_ interaction: UIContextMenuInteraction, willDisplayMenuFor configuration: UIContextMenuConfiguration, animator: UIContextMenuInteractionAnimating?) {
// 在菜单显示之前执行的操作
}
func contextMenuInteraction(_ interaction: UIContextMenuInteraction, willEndFor configuration: UIContextMenuConfiguration, animator: UIContextMenuInteractionAnimating?) {
// 在菜单即将结束时执行的操作
}
func contextMenuInteraction(_ interaction: UIContextMenuInteraction, willPerformPreviewActionForMenuWith configuration: UIContextMenuConfiguration, animator: UIContextMenuInteractionCommitAnimating) {
// 在用户选择菜单项时执行的操作
}
}
这样,当用户长按UIView时,将会显示一个上下文菜单,其中包含"Action 1"和"Action 2"两个菜单项。你可以根据实际需求自定义菜单项的内容和行为。
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