iOS原理之Category的实现原理

//
//  CategoryBasementViewController.swift
//  iOS底层
//
//  Created by yanqunchao on 2019/5/17.
//  Copyright © 2019 yanqunchao. All rights reserved.
//

import UIKit

class CategoryBasementViewController: UIViewController {
    /**
     * 方法类
     */
    class MethodT: NSObject {
        var name:String?
        var type:String?
        var imp:String?
    }
    /**
     * 方法列表类
     */
    class MethodListT: NSObject {
        var size:Int?  //方法列表内存大小
        var methodCount:Int?  //方法数量
        var methodList:[MethodT]?  //方法数组
    }
    /**
     * 只读类类信息
     */
    class ClassRoT: NSObject {
        var name:String = ""
        var baseMethodList:[MethodListT]?  // 实例方法列表
    }
    
    /**
     * 可读可写的类信息
     */
    class ClassRwT: NSObject {
        var ro:ClassRoT?
        var methods:[MethodListT]?  //方法列表
    }
    
    /**
     * 类对象
     */
    class ClassT: NSObject {
        var isa:ClassT?  //指针
        var superClass:ClassT? //父类
        var cache:NSObject?  //方法缓存
        var ro:ClassRoT? //只读类
        var rw:ClassRwT? //可读可写类
        var isRealized:Bool = false //附加信息，标志是否已经处理过分类
    }
    
    /**
     * 分类对象
     */
    class CategoryT: NSObject {
        var name:String = "" //所属类的名称
        var cls:ClassT?   //所属类对象
        var instanceMehthodList:MethodListT?  // 实例方法列表
        var classMethodList:MethodListT? //类方法列表
        var proptocolList:[String]? //协议列表
        var propList:[String]? //属性列表
    }
 
    lazy var categoryArr:[CategoryT] = []
 
    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor = .white
        //获取所有分类
        getAllCategory()
        
        for cat in self.categoryArr { //遍历分类列表
            let cls = cat.cls  //获取到所属类
            
            if cls?.isRealized == false {
                remethodizeClass(cls: cls!) //对所属类重新方法化
            }
        }
    }
    
    //对所属类重新方法化
    func remethodizeClass(cls:ClassT) {
        let cats =  unattachCategoriesForClass(cls: cls)  //分类归类
        if cats.count > 0 {
            attachCategoriesForClass(cls: cls, cats: cats) //合并分类到类中
        }
    }
    
    //合并分类到所属类中
    func attachCategoriesForClass(cls:ClassT,cats:[CategoryT]){
    
        cls.isRealized = true
        
        var methodArrList:[MethodListT] = []
        
        var i = cats.count
        
        while (i != 0) {
            let cat = cats[i - 1]
            let methodList = cat.instanceMehthodList
            methodArrList.append(methodList!)
            i = i - 1
        }
        let oldMethods = cls.rw?.methods?.first
        methodArrList.append(oldMethods!)
        
////        let oldCount = oldMethods?.count
////        let newCount = methodArrList.count + oldCount!
//
         cls.rw?.methods = methodArrList
    }
    
    
    //从分离列表中剥离所属类的分类
    func unattachCategoriesForClass(cls:ClassT) ->[CategoryT] {
        var categroyT:[CategoryT] = []
        
        for cat in self.categoryArr { //遍历分类列表
            if cls.ro?.name == cat.cls?.ro?.name {
                categroyT.append(cat)
            }
        }
        return categroyT
    }
    
    //获取所有分类
    func getAllCategory(){
   
        let baseMethod = MethodT()
        baseMethod.name = "base"
        baseMethod.type = "v16@0:8"
        baseMethod.imp = "MJPerson的base方法地址"
        
        let baseMethodT = MethodListT()
        baseMethodT.size = 1000
        baseMethodT.methodCount = 1
        baseMethodT.methodList = [baseMethod]
  
        let ro =  ClassRoT()
        ro.baseMethodList = [baseMethodT]
        ro.name = "MJPerson"
        
        let cls = ClassT()
        cls.isa = ClassT()
        cls.superClass = ClassT()
        cls.cache = NSObject()
        cls.ro = ro
   
        let rw = ClassRwT()
        rw.ro = ro
        rw.methods = ro.baseMethodList
        cls.rw = rw
        
        let testMethod = MethodT()
        testMethod.name = "test"
        testMethod.type = "v16@0:8"
        testMethod.imp = "MJPerson的test方法地址"
        
        let eatMethod = MethodT()
        
        eatMethod.name = "eat"
        eatMethod.type = "v16@0:8"
        eatMethod.imp = "MJPerson的eat方法地址"
        
        let testMethodList = MethodListT()
        testMethodList.size = 1000
        testMethodList.methodCount = 1
        testMethodList.methodList = [testMethod]
        
        let eatMethodList = MethodListT()
        eatMethodList.size = 1000
        eatMethodList.methodCount = 1
        eatMethodList.methodList = [eatMethod]
        
        
        let categoryTest:CategoryT = CategoryT()
        categoryTest.name = "MJPerson"
        categoryTest.cls = cls
        categoryTest.instanceMehthodList = testMethodList
        
        
        let categoryEat:CategoryT = CategoryT()
        categoryEat.name = "MJPerson"
        categoryEat.cls = cls
        categoryEat.instanceMehthodList = eatMethodList

  
        let cls1 = ClassT()
        cls1.isa = ClassT()
        cls1.superClass = ClassT()
        cls1.cache = NSObject()
        
        let baseMethod1 = MethodT()
        baseMethod1.name = "base"
        baseMethod1.type = "v16@0:8"
        baseMethod1.imp = "MJAnimal的base方法地址"
        
        let baseMethodT1 = MethodListT()
        baseMethodT1.size = 1000
        baseMethodT1.methodCount = 1
        baseMethodT1.methodList = [baseMethod1]
        
        let ro1 =  ClassRoT()
        ro1.baseMethodList = [baseMethodT1]
        ro1.name = "MJAnimal"
        cls1.ro = ro1
        
        let rw1 = ClassRwT()
        rw1.ro = ro1
        rw1.methods = ro1.baseMethodList
        cls1.rw = rw1
        
        let testMethod1 = MethodT()
        testMethod1.name = "test"
        testMethod1.type = "v16@0:8"
        testMethod1.imp = "MJAnimal的test方法地址"
        
        let eatMethod1 = MethodT()
        
        eatMethod1.name = "eat"
        eatMethod1.type = "v16@0:8"
        eatMethod1.imp = "MJAnimal的eat方法地址"
        
        let testMethodList1 = MethodListT()
        testMethodList1.size = 1000
        testMethodList1.methodCount = 1
        testMethodList1.methodList = [testMethod1]
        
        let eatMethodList1 = MethodListT()
        eatMethodList1.size = 1000
        eatMethodList1.methodCount = 1
        eatMethodList1.methodList = [eatMethod1]
        
        let categoryTest1:CategoryT = CategoryT()
        categoryTest1.name = "MJAnimal"
        categoryTest1.cls = cls1
        categoryTest1.instanceMehthodList = testMethodList1
        
        let categoryEat1:CategoryT = CategoryT()
        categoryEat1.name = "MJAnimal"
        categoryEat1.cls = cls1
        categoryEat1.instanceMehthodList = eatMethodList1
        
        self.categoryArr.append(categoryTest1)
        self.categoryArr.append(categoryTest)
        self.categoryArr.append(categoryEat)
        self.categoryArr.append(categoryEat1)
    }
 
}