Establishing Relationships
Having relationships between objects can be a very powerful technique to model the real world in an app. Core Data supports one-to-one and one-to-many relationships. In the sample app, a one-to-many relationship between friends and movies is established. Since a friend might borrow more than one movie at a time, that side of the relationship is “many,” but a movie can be lent to only one friend at a time, so that side of the relationship is “one.”
To add a relationship between entities, select one of the entities, and then Ctrl-click and drag to the destination entity. Alternatively, click and hold the Add Attribute button, and select Add Relationship from the menu that appears. Xcode will create a relationship to the ...
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