可能重复：
Objective-C: alloc of object within init of another object (memory management)
Why does iPhone sample code use so many intermediate variables?
我在Apple的示例代码中注意到您获得了大量代码，例如：
NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] init];
self.fetchedResultsController = aFetchedResultsController;
他们为什么不这样做？：
self.fetchedResultsController = [[NSFetchedResultsController alloc] init];
和另一个例子：
UINavigationController *aNavigationController = [[UINavigationController alloc] initWithRootViewController:rootViewController];
self.navigationController = aNavigationController;
而不是
self.navigationController = [[UINavigationController alloc] initWithRootViewController: rootViewController];
这对我来说似乎是不必要的一步？
谢谢。