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Fetch request
A fetch request tells a managed object context the entity of the managed objects that you want to fetch; optionally, it specifies other aspects such as constraints on the values the objects' properties must have and the order you want the objects returned in. A fetch request is an instance of NSFetchRequest
. The entity it specifies is represented by an instance of NSEntityDescription
; any constraints are represented by an NSPredicate
object, and the ordering by an array of one or more instances of NSSortDescriptor
. These are akin to the table name, WHERE clause, and ORDER BY clauses of a database SELECT statement respectively.
You execute a fetch request by sending a message to a managed object context. The context returns an array containing the objects (if any) that matched the request.
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