Swift：如何过滤核心数据 [英] Swift: How to filter in Core Data

问题描述

我正在使用以下代码来提取类别中的所有数据。

I'm using the following code to fetch all the data in "category".

let appDelegate = UIApplication.sharedApplication().delegate as AppDelegate

let managedContext = appDelegate.managedObjectContext!
let fetchRequest = NSFetchRequest(entityName:"category")
let fetchedResults = managedContext.executeFetchRequest(fetchRequest, error: &error) as [NSManagedObject]?

我如何只带类型等于产品的类别？

How do I only brings categories where the "type" is equal to "products"?

推荐答案

要过滤 Core Data中的结果，请使用 NSPredicate ，如下所示：

To "filter" results in Core Data, use NSPredicate like so:

let filter = "products"
let predicate = NSPredicate(format: "type = %@", filter)
fetchRequest.predicate = predicate

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