iOS 多层block

- (void)setShiFangUpModel{undefined
    SFModel *model = [SFModel new];
   
    __weak typeof(self) weakSelf = self;

    model.chuanZhiBlock = ^(NSString *title) {undefined

        __strong typeof(self) strongSelf = weakSelf;//第一层
        strongSelf.titleLabel.text = title;
        
        __weak typeof(self) weakSelf2 = strongSelf;
        strongSelf.model.chuanZhiBlock = ^(NSString *title2) {undefined

            __strong typeof(self) strongSelf2 = weakSelf2;//第二层
            strongSelf2.titleLabel.text = title2;
        };
    };