macos 核心数据：获取所有实体
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Core Data: Fetch all entities
提问by xhan
I want to know is there an equivalent to the MySQL SELECT * FROM table ORDER BY sthto fetch all the results.
我想知道是否有等效于 MySQLSELECT * FROM table ORDER BY sth来获取所有结果。
回答by Barry Wark
Use an NSFetchRequestwith a nilpredicate and an appropriate NSSortDescriptor. On iOS, you should be using an NSFetchedResultscontroller as the query may return more items that you want in memory at once.
使用NSFetchRequest带有nil谓词和适当的NSSortDescriptor. 在 iOS 上，您应该使用NSFetchedResults控制器，因为查询可能会一次返回更多您想要在内存中的项目。
回答by Frank C.
Xhan,
赞，
The 'grammar' may be equivalent but there is some work you have to do in the application. A good starting explanation is Here.
“语法”可能是等价的，但您必须在应用程序中做一些工作。一个很好的开始解释是Here。
In general you'd want to setup a NSFetchRequestwith the appropriate filters, sorts, etc. that you need.
通常，您希望NSFetchRequest使用您需要的适当过滤器、排序等来设置。
-- Frank
——弗兰克
