Swift中NSFetchRequest的多个NSPredicates？

Question

目前,我有一个简单的NSFetchRequest与相关的NSPredicate.但是,我希望有一种方法可以追加多个谓词.我在Objective C中看到了一些例子,但没有看到Swift的例子.

你能定义一个NSPredicate列表,或者以某种方式将多个NSPredicate对象附加到单个NSFetchRequest中吗？

谢谢!

Answer 1

您可以使用"NSCompoundPredicate".例如:

    let converstationKeyPredicate = NSPredicate(format: "conversationKey = %@", conversationKey)
    let messageKeyPredicate = NSPredicate(format: "messageKey = %@", messageKey)
    let andPredicate = NSCompoundPredicate(type: NSCompoundPredicateType.AndPredicateType, subpredicates: [converstationKeyPredicate, messageKeyPredicate])
    request.predicate = andPredicate

您可以更改为"AndPredicateType"或"OrPredicateType"

Answer 2

Swift 4的更新

        let predicateIsNumber = NSPredicate(format: "isStringOrNumber == %@", NSNumber(value: false))
        let predicateIsEnabled = NSPredicate(format: "isEnabled == %@", NSNumber(value: true))
        let andPredicate = NSCompoundPredicate(type: .and, subpredicates: [predicateIsNumber, predicateIsEnabled])

        //check here for the sender of the message
        let fetchRequestSender = NSFetchRequest<NSFetchRequestResult>(entityName: "Keyword")
        fetchRequestSender.predicate = andPredicate

最新的Swift版本的变化是:

NSCompoundPredicateType.AndPredicateType replaced by `NSCompoundPredicate.LogicalType.and `

希望能帮助到你!!!

谢谢