SwiftUI macOS 命令(菜单栏)和视图 [英] SwiftUI macOS Commands (menu bar) and View

问题描述

我开始学习 SwiftUI 和 macOS 开发.我正在使用 SwiftUI 生命周期.如何从菜单栏中的聚焦窗口调用函数.

Hi I am starting to learn SwiftUI and macOS development. I am using the SwiftUI life cycle. How do I call a function from the focused window from the menu bar.

除了 Apple 文档之外，我还找到了此参考资料，并且是能够使用命令创建菜单项，但我不知道如何从我的视图中调用函数.

Besides Apple documentation, I found this reference and am able to create menu items using Commands but I have no idea how to call a function from my view.

例如:

假设这是我的应用程序结构:

Suppose this is my App struct:

import SwiftUI

@main
struct ExampleApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }.commands {
        CommandMenu("First menu") {
            Button("Action!") {
                // How do I call the views action function?
            }
        }
    }
}

这是我的观点:

struct ContentView: View {
    public func action() {
        print("It works")
    }
    var body: some View {
        Text("Example")
    }
}

如果有任何错别字，抱歉我只是输入了示例代码，但我希望你能理解.

I just typed the example code sorry if there are any typos but I hope you can get the idea.

推荐答案

因为 SwiftUI 中的 View 是瞬态的，你不能持有对 ContentView 调用一个函数.不过，您可以做的是更改传递给内容视图的部分状态.

Because Views in SwiftUI are transient, you can't hold a reference to a specific instance of ContentView to call a function on it. What you can do, though, is change part of your state that gets passed down to the content view.

例如:

@main
struct ExampleApp: App {
    @StateObject var appState = AppState()
    
    var body: some Scene {
        WindowGroup {
            ContentView(appState: appState)
                .frame(maxWidth: .infinity, maxHeight: .infinity)
        }.commands {
            CommandMenu("First menu") {
                Button("Action!") {
                    appState.textToDisplay = "\(Date())"
                }
            }
        }
    }
}

class AppState : ObservableObject {
    @Published var textToDisplay = "(not clicked yet)"
}

struct ContentView: View {
    @ObservedObject var appState : AppState
    
    var body: some View {
        Text(appState.textToDisplay)
    }
}

注意 .commands 修饰符继续 WindowGroup { }

Note that the .commands modifier goes on WindowGroup { }

在这个例子中，AppState 是一个 ObservableObject，它保存了应用程序的一些状态.它使用参数传递给 ContentView.您还可以通过环境对象(https://www.hackingwithswift.com/quick-start/swiftui/how-to-use-environmentobject-to-share-data-between-views)

In this example, AppState is an ObservableObject that holds some state of the app. It's passed through to ContentView using a parameter. You could also pass it via an Environment Object (https://www.hackingwithswift.com/quick-start/swiftui/how-to-use-environmentobject-to-share-data-between-views)

单击菜单项时，它会设置 textToDisplay，它是 AppState 上的 @Published 属性.ContentView 将在 AppState 的 @Published 属性更新时更新.

When the menu item is clicked, it sets textToDisplay which is a @Published property on AppState. ContentView will get updated any time a @Published property of AppState gets updated.

这是您将使用的模式的总体思路.如果您有此模式未涵盖的用例，请在评论中告诉我.

This is the general idea of the pattern you'd use. If you have a use case that isn't covered by this pattern, let me know in the comments.

更新，根据您的评论:

import SwiftUI
import Combine

@main
struct ExampleApp: App {
    @StateObject var appState = AppState()
    
    var body: some Scene {
        WindowGroup {
            ContentView(appState: appState)
                .frame(maxWidth: .infinity, maxHeight: .infinity)
        }.commands {
            CommandMenu("First menu") {
                Button("Action!") {
                    appState.textToDisplay = "\(Date())"
                }
                Button("Change background color") {
                    appState.contentBackgroundColor = Color.green
                }
                Button("Toggle view") {
                    appState.viewShown.toggle()
                }
                Button("CustomCopy") {
                    appState.customCopy.send()
                }
            }
        }
    }
}

class AppState : ObservableObject {
    @Published var textToDisplay = "(not clicked yet)"
    @Published var contentBackgroundColor = Color.clear
    @Published var viewShown = true
    
    var customCopy = PassthroughSubject<Void,Never>()
}

class ViewModel : ObservableObject {
    @Published var text = "The text I have here"
    var cancellable : AnyCancellable?

    func connect(withAppState appState: AppState) {
        cancellable = appState.customCopy.sink(receiveValue: { _ in
            print("Do custom copy based on my state: \(self.text) or call a function")
        })
    }
}

struct ContentView: View {
    @ObservedObject var appState : AppState
    @State var text = "The text I have here"
    @StateObject private var viewModel = ViewModel()
    
    var body: some View {
        VStack {
            Text(appState.textToDisplay)
                .background(appState.contentBackgroundColor)
            if appState.viewShown {
                Text("Shown?")
            }
        }
        .onReceive(appState.$textToDisplay) { (newText) in
            print("Got new text: \(newText)")
        }
        .onAppear {
            viewModel.connect(withAppState: appState)
        }
    }
}

在我的更新中，您可以看到我已经解决了背景颜色的问题，显示隐藏视图，甚至在 @Published 属性之一时收到通知(通过 onReceive)变化.

In my updates, you can see that I've addressed the question of the background color, showing hiding a view, and even getting a notification (via onReceive) when one of the @Published properties changes.

您还可以看到我如何使用自定义发布者 (customCopy) 将操作传递给 ContentView 的 ViewModel

You can also see how I use a custom publisher (customCopy) to pass along an action to ContentView's ViewModel

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