21.swift-block循环引用

1.实现:

import UIKit

class AFNetHttp: NSObject {
    
    
    ///1.读取数据
    func loadData(callBack : @escaping (_ block : String)->()) {
        
        DispatchQueue.global().async {
            print("异步:",Thread.current);
            
            DispatchQueue.main.sync {
                print("同步:",Thread.current);
                
                //调用闭包
                callBack("callBack");
            }
        }
    }
    
///2.block作为类型
    var callBlock : ((_ call : String)->())?
  
    func getData(call : @escaping (_ block : String)->()) {
        
        self.callBlock = call;
        
        DispatchQueue.global().async {
            print("异步:",Thread.current);
            
            DispatchQueue.main.sync {
                print("同步:",Thread.current);
                
                //调用闭包
                call("call");
            }
        }
    }
    
}

2.调用:

import UIKit

class BlockViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }
    
    ///1.手指开始点击
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        ///实现方法
        ///解决循环引用 [weak self]
        AFNetHttp.init().loadData {[weak self] (block) in
            print("viewController : ",block);
            self?.view.backgroundColor = UIColor.red;
        }
    }
    
    ///2.手指开始移动
    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        ///解决循环引用 [weak self]
        AFNetHttp.init().getData {[weak self] (call) in
            self?.view.backgroundColor = UIColor.yellow;
            
        }
    }
    
    ///
    deinit {
        print("销毁");
    }

}