Swift:如何在Core Data中过滤

Question

我正在使用以下代码来获取"类别"中的所有数据.

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]?

我如何只提供"类型"等于"产品"的类别？

Answer 1

要在Core Data中"过滤"结果,请使用NSPredicate如下:

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