如何确认 AppDelegate 的 ObservableObject？

Posted 2023-02-24

【中文标题】如何确认 AppDelegate 的 ObservableObject？

【英文标题】：How to confirm ObservableObject for an AppDelegate?

【发布时间】：2020-07-20 15:23:24

【问题描述】：

我正在尝试观察 macOS AppDelegate 中的值，但出现错误

ContentView.swift:14:6：通用结构“ObservedObject”需要“NSApplicationDelegate？”符合'ObservableObject'

当我尝试使用as! ObservedObject 将对象转换为ObservedObject 时，我遇到了另一个错误

ContentView.swift:14:6：通用结构“ObservedObject”要求“ObservedObject”符合“ObservableObject”

AppDelegate.swift 文件内

import Cocoa
import SwiftUI
import Combine

@NSApplicationMain
class AppDelegate: NSObject, ObservableObject, NSApplicationDelegate  
    var isFocused = true
    
    // Other code app life-cycle functions

ContentView.swift 文件内

import SwiftUI
import Combine

struct ContentView: View 
    @ObservedObject var appDelegate = NSApplication.shared.delegate
    
    // Other UI code

【参考方案1】：

这看起来像是概念的混合......我建议避免这样......而是创建显式可观察类。

如下图（略）

class AppState: ObservableObject 
  @Published var isFocused = true


@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate  
    var appState = AppState()
    
    // Other code app life-cycle functions

     // in place where ContentView is created
     ...
     ContentView().environmentObject(self.appState)
     ...

在 ContentView 中使用它

struct ContentView: View 
    @EnvironmentObject var appState: AppState
    
    // Other UI code

    var body: some View 
       // .. use self.appState.isFocused where needed