iOS原理之Block的访问auto变量(static类型)的实现原理

//
//  BlockBasementStaticTypeAutoViewController.swift
//  iOS底层
//
//  Created by yanqunchao on 2019/5/19.
//  Copyright © 2019 yanqunchao. All rights reserved.
//

import UIKit

class BlockBasementStaticTypeAutoViewController: UIViewController {
    typealias FuncPt = ((MainBlockImpl0)->())
  
    class BlockImpl: NSObject {
        var isa:UnsafeRawPointer?
        var Flags:Int?
        var Reserved:Int?
        var FuncPtr:FuncPt? //函数地址，
    }
    /*
     * 访问auto局部变量的Desc类
     **/ 
    class MainBlockDesc0: NSObject {
        var reserved:Int?
        var BlockSize:Int?
        
        init(reserve:Int,blockSize:Int) {
            reserved = reserve
            BlockSize = blockSize
        }
        
        override init() {
            
        }
        
    }
    /*
     * 访问static局部变量的block类
     **/ 
    class MainBlockImpl0: NSObject {
        var imp: BlockImpl?
        var Desc: MainBlockDesc0?
        var height: UnsafeMutablePointer? //局部变量的地址
        init(fp:@escaping FuncPt,Desc:MainBlockDesc0,flag:Int,height:UnsafeMutablePointer) {
            imp = BlockImpl()
//            imp!.isa = &_NSConcreateStackBlock
            imp?.Flags = flag
            imp?.FuncPtr = fp
            self.Desc = Desc
            self.height = height
        }
        override init() {

        }
    }
    /*
     *block调用的函数地址
     **/
    func mainBlockFunc0(block:MainBlockImpl0){
        print("调用mainBlockFunc0函数获取的变量值为\(block.height!.pointee)))")
    }

    
    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }
    

    
    func blockWithStaticLocalVar(){ // 访问static类型的局部变量的block

        var staticHeight:Int = 10 //假设是静态局部变量(swift无法创建局部静态变量，无法模拟其场景) 
     
        let mainBlockDesc0Data = MainBlockDesc0(reserve: 0, blockSize: MemoryLayout.size(ofValue: MainBlockImpl0.self))

        let block = MainBlockImpl0(fp: mainBlockFunc0, Desc: mainBlockDesc0Data,flag: 0, height: &staticHeight)

        staticHeight = 20

        block.imp?.FuncPtr!(block)
    }

}