10、Swift 编程中的扩展与协议扩展：功能增强与实用指南

Swift 编程中的扩展与协议扩展：功能增强与实用指南

1. 协议与协议导向编程

在编程领域，协议导向编程是一种重要的编程范式，而协议则是其核心所在。协议就像是协议导向编程的支柱，理解协议对于正确实现协议导向编程至关重要。

例如，有如下代码定义了一个绿带高级的跆拳道等级结构体：

let focusPadDrills = ["Reverse Punch", "Number 1 Front Kick"]
let focusPadMissesAllowed = 2

struct GreenBeltSenior: TKDRankProtocol, FormProtocol,
          BoardBreakProtocol, FocusPadProtocol, SparringProtocol {
    let color = TKDBeltColors.Green
    let rank = TKDColorRank.NoRank
    let formName = "Do-San"
    let focusPadDrills = ["Back Fist", "Number 2 Crescent"]
    let focusPadMissesAllowed = 2
    let boardBreaks = [(name:"Hammer Fist", required: false),
                       (name:"Front Kick", required: false)]
    let boardBreaksRequired = 1
    let sparringRou