低内存/应用程序崩溃？

Question

这是我的代码： -

NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
[fetchRequest setEntity:[NSEntityDescription entityForName:@"PageDetail" inManagedObjectContext:managedObjectContext]];
NSError *error = nil;
NSMutableArray *mutableFetchResults = [[managedObjectContext executeFetchRequest:fetchRequest error:&error] mutableCopy];//memory 55.7%
[self setPagesArray:mutableFetchResults];
[fetchRequest release];
[mutableFetchResults release];

我已经释放了内存，但它在此行/代码上显示为内存不足

NSMutableArray *mutableFetchResults = [[managedObjectContext executeFetchRequest:fetchRequest error:&error] mutableCopy];//memory 55.7%

请纠正或建议我，我做错了。在此先感谢。