iOS循环引用

class ViewController: UIViewController {
    // 1.闭包是当前类属性
    var allCallBack :(()->())?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        CyclicLead {
            // 闭包引用当前类
            print(self.view)
        }
    }

    // 循环引用的方法
    func CyclicLead(completionBack:@escaping ()->()) -> Void {
        // 2.当前类引用闭包
        allCallBack = completionBack
        
        DispatchQueue.global().async {
            
            DispatchQueue.main.async {
                completionBack()
            }
        }
    }
    
    // 当对象销毁时会调用
    deinit {
        print("销毁了")
    }
}

__weak typeof(self) weakSelf = self;
self.block = ^(NSString *name){
    NSLog(@"view:%@", weakSelf.view);
};

__unsafe_unretained typeof (self) weakSelf = self;
[self loadData:^{
    NSLog(@"%@", weakSelf.view);
}];

    // 解决方案一:
    /*
    细节1：var ,weak 只能修饰var，不能修饰 let
     'weak' must be a mutable variable,
      because it may change at runtime
      weak 可能会被在运行时被修改 -> 指向的对象一旦被释放，会被自动设置为nil
    细节2: weakSelf?  weakSelf!   两种解包方式
    ？可选解包 - 如果self已经被释放，不会向对象发送getter消息
        可选解包只是单纯的发送消息，没有计算
    ! 强行解包 - 如果self已经被释放，强行解包会导致崩溃
        强行解包可以参与计算，可选项不能直接参与到计算
    */
    weak var weakSelf = self
    CyclicLead {
        print(weakSelf?.view)
    }

CyclicLead {[weak self]()->() in            
    print(self?.view)
}
// 缩减写法
CyclicLead {[weak self] in
    print(self?.view)
}

CyclicLead {[unowned self]()->() in
    print(self?.view)
}

// 缩减写法
CyclicLead {[unowned self] in
    print(self?.view)
}