Swift:如何在 Core Data 中进行过滤

Question

我正在使用以下代码获取“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]?

如何只引入“类型”等于“产品”的类别？

Answer 1

要在 Core Data 中“过滤”结果，请像这样使用 NSPredicate:

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