persist

问题 I\'ve been creating a list app and backing it with core data. I would like to have a default list of say 10 airport\'s items, so that the user doesn\'t have to start from scratch. Is there any way to do this? Any help is appreciated. Thanks in advance. 回答1: Here's the best way (and doesn't require SQL knowledge): Create a quick Core Data iPhone app (Or even Mac app) using the same object model as your List app. Write a few lines of code to save the default managed objects you want to the

问题 EntityManager.merge() can insert new objects and update existing ones. Why would one want to use persist() (which can only create new objects)? 回答1: Either way will add an entity to a PersistenceContext, the difference is in what you do with the entity afterwards. Persist takes an entity instance, adds it to the context and makes that instance managed (ie future updates to the entity will be tracked). Merge creates a new instance of your entity, copies the state from the supplied entity, and