核心数据3从索引

Question

let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
do{
  cards = try context.fetch(Card.fetchRequest()).
  }
catch{
  print(error)
  }

此代码读取整个海量数据。如果我只想从id读取怎么办？喜欢这里＆＃34; id ==％@＆＃34;。这该怎么做？如何编辑来自id的数据？

Answer 1

let request = NSFetchRequest<MenuItems>(entityName: "MenuItems")
let filters = NSPredicate(format: "id == %@", id)

request.predicate = NSCompoundPredicate(andPredicateWithSubpredicates: [filters])

let results = (try? context.fetch(request)) ?? []

如果您愿意，可以向NSPredicate添加更多filters。