Core Data singleton manager?

Question

What technical reasons are there not to make a singleton class to manage my Core Data? I\'m trying to make a decision now, if I should strip out all of the boilerplate core data

Answer 1

There are two important considerations (note these are not the only two) when deciding if a singleton is right for you:

1. Threading
2. Memory Usage

Threading

Singletons are convenient, but if your application uses multiple threads you might be tempted to write something like this:

[[CDSingleton managedObjectContext] executeFetchRequest:someFetch];
//later on a background thread you might write
NSManagedObject *object = [[CDSingleton managedObjectContext] objectWithID:objectID];

Shortly after that, your application will crash because you've accessed a managedObjectContext which was likely created on the main thread from some other thread.

Memory Usage

Singletons never go away, that's the point of a Singleton. Thus, they also never willingly free their consumed resources. In the case of CoreData that means the managed object context will continue to hold managed objects in memory until you call -reset or -save:.

That could be bad if your app uses a lot of data.