核心日期概念：NSFetchedResultsController与NSManagedObject objectsWithFetchRequest [英] Core Date Concept: NSFetchedResultsController vs. NSManagedObject objectsWithFetchRequest

问题描述

何时使用 NSFetchedResultsController 与进行比较NSManagedObject中的objectsWithFetchRequest 方法？有典型的情况吗？

解决方案

objectsWithFetchRequest：（或 executeFetchRequest：错误：）只是执行获取请求并返回结果集。

A NSFetchedResultsController 执行提取请求，然后监视对数据存储的更改（或更精确地说，对受管理对象上下文的更改）。如果对象被添加/删除/修改，导致获取请求的结果集更改，它会调用代理函数报告更改。

A NSFetchedResultsController 在大多数情况下用于使用获取请求的结果填充表视图，并在对象被插入，删除或更改时自动更新表视图。

When do I use a NSFetchedResultsController in comparsion to the objectsWithFetchRequest method in NSManagedObject? Are there typical scenarios?

解决方案

objectsWithFetchRequest: (or executeFetchRequest:error:) just executes a fetch request and returns the result set.

A NSFetchedResultsController executes a fetch request and then monitors changes to the data store (or more precisely, changes to the managed object context). If objects are added/deleted/modified that cause the result set of the fetch request to change, it calls delegate functions to report the change.

A NSFetchedResultsController is in most cases used to populate a table view with the result of a fetch request, and automatically update the table view if objects are inserted, deleted or changed.

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