ios - 如何在调用 dealloc 后停止运行 block ？ 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类会在后台发送http Request，然后在CompletedBlock上运行。

我的问题:有时系统会释放当前 View Controller ，然后调用 onCompleted block ，并在 [lstSubCategoriesBlock reloadData] 上崩溃，因为它已经释放。

我应该怎么做，以防止系统在释放 viewContorller 时执行 [lstSubCategoriesBlock reloadData]？

Answer 1

使用 __weak 这样当对象被释放时它指向 nil

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

    }]ExecuteRequest];