Publisher

发布者向一个或多个订阅者发送值。它们遵循Publisher协议，并声明输出的类型和它们产生的任何错误:

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public protocol Publisher {
  associatedtype Output
  associatedtype Failure : Error
  func receive<S>(subscriber: S) where S : Subscriber, Self.Failure == S.Failure, Self.Output == S.Input
}

发布者可以随时间发送任意数量的值，也可以发送错误而失败。关联类型Output定义发布者可以发送哪些类型的值，而关联类型Failure定义它可能失败的错误类型。发布者可以通过指定never关联类型来声明它永远不会失败。

通过组合 事件处理操作符 自定义异步事件的处理。

Customize handling of asynchronous events by combining event-processing operators.

Getting Started

SwiftUI’s reactive state management makes this a lot easier by introducing the notion of a source of truth that can be shared across your app using SwiftUI’s property wrappers such as @EnvironmentObject, @ObservedObject, and @StateObject

the notion of a source of truth 事实源
This source of truth usually is your in-memory data model

In this series, we will look at how to use Combine in the context of SwiftUI to

• access the network,
• map data,
• handle errors

Scene

A scene contains the view hierarchy of your app.

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import SwiftUI


@main
struct MyApp: App {
    var body: some Scene {
        WindowGroup {
            TabView {
                ContentView()
                    .tabItem {
                        Label("Journal", systemImage: "book")
                    }
                SettingsView()
                    .tabItem {
                        Label("Settings", systemImage: "gear")
                    }
            }
        }
    }
}

In this sample, body returns the primary scene WindowGroup, which describes the view hierarchy of the sample’s main window.

WindowGroup: It provides platform-specific behaviors for your app, such as supporting multiple windows in macOS and iPadOS.

The computed body property can return one or more primary and secondary scenes.

常用的宏方法

@main

The @main attribute identifies the app’s entry point.

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import SwiftUI


@main
struct MyApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}

The entry point is responsible for the start up of the app.

The MyApp structure conforms to the App protocol,

The structure implements the computed property body, which is a requirement of the App protocol.

SwiftUI provides different types of scenes including WindowGroup, Window, DocumentGroup, and Settings

一些在后台运行的任务，需要在特定条件下对用户发起通知，如果有跨端要求，可以用第三方库，不过需要付费，优势在于可同时兼容移动端和桌面端，这里只是个人使用，所以推荐使用Mac自带Apple Script来添加，本来考虑通过向Reminders添加Event的方式，实现Mack & iOS同时提醒，不过只找到OC和Swift的API，没找到Py的API

机器学习是人工智能的一个分支。人工智能的研究历史有着一条从以“推理”为重点，到以“知识”为重点，再到以“学习”为重点的自然、清晰的脉络。

机器学习是实现人工智能的一个途径之一，即以机器学习为手段，解决人工智能中的部分问题。

环境：
Mac OS Monterey 12.5.1
MacBook Air (M1, 2020)
Xcode 14.1
Python 3.11.5