ios - NSPredicate 按名称传递 "multiple"参数 [在 Swift 中]

Question

是否可以通过命名而不是 %@

将多个参数传递给 NSPredicate

例如，我有一个直接传递参数me和you。

public static func ConversationByUserId( userId : String ) -> [Message] {

    // Either Created By me and sent to you.
    // Or, created by you and sent to me


    let me = UserRepo.GetLoggedInUser()?.id

    var format = "( createdBy == '" + me! + "'  && createdTo == '"  +  userId + "') "
    format += " || ( createdBy == '" + userId + "'  && createdTo == '" + me! + "') "


    print(format)
    //prints: ( createdBy == '1'  && createdTo == '5')  || ( createdBy == '5'  && createdTo == '1')


    let predicate = NSPredicate(format:  format)

    return Filter(predicate);


}

注意:Filter(predicate) 执行操作并返回结果。到目前为止，一切都很好。我得到了预期的结果。但我猜这可能会产生像 SQL 攻击这样的问题。

我可以做如下的事情吗:如果可以，怎么做？

  var format = "( createdBy == @me  && createdTo == @you ) "
  format += " || ( createdBy == @you  && createdTo == @me ) "


 let predicate = NSPredicate(format:  format, [ "me" : me, "you" : you ])

到目前为止我取得的成绩是:

    format = "( createdBy == %@  && createdTo == %@ ) "
    format += " || ( createdBy == %@  && createdTo == %@ ) "


    let predicate = NSPredicate(format:  format, me!, you, me!, you)

Answer 1

您可以使用 NSPredicate 的 predicateWithSubstitutionVariables(参见 Apple Docs)。像往常一样创建谓词，使用“$variable”代替您要替换的值:

var format = "( createdBy == $me  && createdTo == $you ) "
format += " || ( createdBy == $you  && createdTo == $me ) "
let predicate = NSPredicate(format:  format)

然后用变量名和你想传递的值创建一个字典:

let subVars = ["me" : me!, "you" : you!]

最后用您的值替换变量名创建谓词:

let finalPredicate = predicate.predicateWithSubstitutionVariables(subVars)