What is Combine?

• A declarative Swift API for processing values over time
• "Customize handling of asynchronous events by combining event-processing operators."

Combine是用于处理事件流的声明式编程框架

大部分介绍Combine文章的第一个示例大致如下：

Just(5)
    .map { _ -> String in
        // do something with the incoming value here
        // and return a string
        "a string"
    }
    .sink { receivedValue in
        // sink is the subscriber and terminates the pipeline
        print("The end result was \(receivedValue)")
    }

它清晰的描述了发布者Publisher，操作符Operator，订阅者Subsciber三者间的关系，对有reactive programming编程经验的开发者而言更是一目了然

没接触过函数响应式编程的朋友请阅读：Using Combine - 函数响应式编程

关于 Combine 的核心概念请阅读：Using Combine - 核心概念

import Combine

[1, 2, 3].publisher
    .map { int in "Number: \(int)" }
    .sink(receiveValue: { int in
        print(int)
    })

[1, 2, nil, 3, nil, 4, nil, 5].publisher
    .compactMap { $0 }
    .sink(receiveValue: { int in
        print("Received \(int)")
    })