//

//  ViewController4.swift

//  SwiftBasicDemo

//

//  Created by 思 彭 on 16/11/16.

//  Copyright © 2016年 思 彭. All rights reserved.

// 协议和扩展

import UIKit

// 定义协议

protocol ExampleProtocol {

    var simpleDescription: String {

        get

    }

    // 使用 mutating 关键字修饰方法是为了能在该方法中修改 struct 或是 enum 的变量，在设计接口的时候，也要考虑到使用者程序的扩展性。所以要多考虑使用mutating来修饰方法。

    mutating func adjust()

}

class ViewController4: UIViewController {

    override func viewDidLoad() {

        super.viewDidLoad()

        self.title = "协议和扩展"

        // 1.Classes, enumerations, and structs都能接受协议

        var a = SimpleClass()

        a.adjust()

        let aDescription = a.simpleDescription

        print("aDescription = \(aDescription)")

        var b = SimpleStructure()

        b.adjust()

        let bDescription = b.simpleDescription

        print("bDescription = \(bDescription)")

        // 输出结果：

        /* aDescription = A very simple class.  Now 100% adjusted.

           bDescriptionA = simple structure (adjusted)

        */

        // 2. extension扩展的使用

        print(.simpleDescription)}   // The number 7

    }

    // 创建类,遵守协议

    class SimpleClass: ExampleProtocol {

        var simpleDescription: String = "A very simple class."

        var anotherProperty: Int =

        func adjust() {

            simpleDescription += "  Now 100% adjusted."

        }

    }

    struct SimpleStructure: ExampleProtocol {

        var simpleDescription: String = "A simple structure"

        mutating func adjust() {

            simpleDescription += " (adjusted)"

        }

    }

    // Int的扩展

    extension Int: ExampleProtocol {

        var simpleDescription: String {

            return "The number \(self)"

        }

        mutating func adjust() {

            self +=

        }

}