调用dealloc后如何停止运行块？ IOS

Question

我有这段代码：

__block NSMutableArray *subCategoriesBlock = self.subCategories ;
__block UITableView *lstSubCategoriesBlock = self.lstSubCategories;
[[AsyncRequest initRequest: onCompletedBlock:^(NSMutableArray *subcategories) {
        [subCategoriesBlock addObjectsFromArray:subcategories];
        [lstSubCategoriesBlock reloadData];

    }]ExecuteRequest];

AsyncRequest类将在后台发送http请求，然后运行onCompletedBlock。

我的问题： 有时系统会释放当前视图控制器，然后调用onCompleted块，并在[lstSubCategoriesBlock reloadData]上崩溃，因为它已经解除分配。

我应该怎么做，以防止系统在重新发布viewContorller时执行[lstSubCategoriesBlock reloadData]？

Answer 1

使用__weak以便在取消分配对象时，它指向nil

__block __weak NSMutableArray *subCategoriesBlock = self.subCategories ;
__block __weak UITableView *lstSubCategoriesBlock = self.lstSubCategories;
[[AsyncRequest initRequest: onCompletedBlock:^(NSMutableArray *subcategories) {
        [subCategoriesBlock addObjectsFromArray:subcategories];
        [lstSubCategoriesBlock reloadData];

    }]ExecuteRequest];