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How can I tell whether an NSManagedObject is persisted?
(As opposed to a new object that has not beed saved yet or was deleted.)
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You cannot pass NSManagedObjects between multiple contexts, but you can pass NSManagedObjectIDs and use them to query the appropriate context for the object represented by that ID.
Right-click on your project's folder in the project navigator and then New File… In the new window, type “data” in the top right corner, select Data Model, and press Next. Give it a name, and save it. Now, let's add all the necessary code to connect Core Data with our project.
From your perspective, the context is the central object in the Core Data stack. It's the object you use to create and fetch managed objects, and to manage undo and redo operations. Within a given context, there is at most one managed object to represent any given record in a persistent store.
In some respects, an NSManagedObject acts like a dictionary—it's a generic container object that provides efficient storage for the properties defined by its associated NSEntityDescription instance.
check if its object id is persistent
BOOL isSaved = !object.objectID.isTemporaryID;
documentation about isTemporaryID:
"YES if the receiver is temporary, otherwise NO. Most object IDs return NO. New objects inserted into a managed object context are assigned a temporary ID which is replaced with a permanent one once the object gets saved to a persistent store."
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