ios - 我如何在单个获取请求中调用两个 NSPredicate。核心数据 iOS Swift

Question

在我的应用程序中，我使用的是 Core Data。现在我想从数据库中获取数据，为此我正在使用获取请求。但我想在单个获取请求中使用两个 NSPrediate，所以我该怎么做。

这是我的代码:

let feedfetch = NSFetchRequest(entityName: "Feed")
feedfetch.predicate = NSPredicate(format: "userid == %@", userid)

let fetchedPerson = try moc.executeFetchRequest(feedfetch)

但是我想使用两个或更多谓词，那么我该怎么做呢？

我想在一个获取请求中调用所有这些，我该怎么做

let feedfetch = NSFetchRequest(entityName: "Feed")
feedfetch.predicate = NSPredicate(format: "userid == %@", userid)
feedfetch.predicate = NSPredicate(format: "is_deleted == %@", "0")
let sortDescriptor = NSSortDescriptor(key: "feed_id", ascending: false,selector: #selector(NSString.localizedStandardCompare))
feedfetch.sortDescriptors = [sortDescriptor]

let fetchedPerson = try moc.executeFetchRequest(feedfetch)

Answer 1

如果您出于任何原因需要使用两个谓词(NSPredicate 对象)而不是一行:

"(userid == %@) AND (is_deleted == %@)"

然后使用NSCompoundPredicate API:

feedfetch.predicate = NSCompoundPredicate(type:.AndPredicate, subpredicates:[
    NSPredicate(format: "userid == %@", userid), 
    NSPredicate(format: "is_deleted == %@", "0")])