Swift标准库中的协议_012_swift协议

//: Playground - noun: a place where people can play

import UIKit

//--Swift标准库中的协议---//

//1.实例的比较：判断两个实例值是否相同
let a = 4, b = 4
a == b //(Int类型的比较)

//自定义结构体类型，进行是否相等的比较
struct Games {

    var winCount : Int
    var loseCount : Int
}

let g1 = Games(winCount: 2, loseCount: 1)
let g2 = Games(winCount: 2, loseCount: 1)

//g1 == g2

//自定义类型判断是否相等需要遵守协议Equatable

extension Games : Equatable {}

//==为方法名，因为此协议方法是通过＝＝来调用
func ==(g1 : Games, g2 : Games) -> Bool {

    return g1.winCount == g2.winCount && g1.loseCount == g2.loseCount

}

if g1 == g2 {
    print("相同")
} else {
    print("不同")
}

//2.比较两个实例的大小 Comparable
extension Games : Comparable {}

//协议方法实现的逻辑由编程者自己定义，要符合常规的逻辑
func <(g1 : Games, g2 : Games) -> Bool {

    let gScore1 = g1.winCount - g1.loseCount
    let gScore2 = g2.winCount - g2.loseCount

    return gScore1 < gScore2
}

g1 < g2

//3.哈希协议
class Student {

    var ID : Int?
    var name : String?

    init(ID: Int, name:String) {

        self.ID = ID
        self.name = name
    }
}

extension Student : Hashable {
    //扩展计算属性hashValue
    var hashValue : Int {

        return ID!

    }

}
//Hashable继承自Equatable协议，因此必须实现==协议方法
func ==(s1 : Student, s2 : Student) -> Bool {

    return s1.ID == s2.ID

}

var s1 = Student(ID: 1000, name: "kathy")
var s2 = Student(ID: 1001, name: "Tom")

let stuSet : Set<Student> = [s1, s2, s2, s2]
stuSet.count

let stuDic : [Student : String] = [s1 : "Class 1", s2 : "Class 2"]

stuDic.count