nspredicate - 使用 "CONTAINS"运算符时，带有 NSPredicate 的 CKQuery 失败

Question

根据 Apples 类引用 CKQuery，运算符 CONTAINS 是受支持的运算符之一。但是，这似乎不起作用。我有一个名为 myRecord 的 RecordType，以及一个字段名称为 name 类型为 String 的记录。我尝试使用两种不同的谓词获取记录，一种使用“==”运算符，另一种使用CONTAINS 运算符。

func getRecords() {
    let name = "John"
    let Predicate1 = NSPredicate(format: "name == %@",name)
    let Predicate2 = NSPredicate(format: "name CONTAINS %@",name)

    let sort = NSSortDescriptor(key: "Date", ascending: false)
    let query = CKQuery(recordType: "myRecord", predicate: Predicate1)
    // let query = CKQuery(recordType: "myRecord", predicate: Predicate2)
    query.sortDescriptors = [sort]

    let operation = CKQueryOperation(query: query)
    operation.desiredKeys = ["name", "Date"]

    operation.recordFetchedBlock = { (record) in
        print(record["name"])

        operation.queryCompletionBlock = { [unowned self] (cursor, error) in
            dispatch_async(dispatch_get_main_queue()) {
                if error == nil {

                    print ("sucess")
                } else {
                    print("couldn't fetch record error:\(error?.localizedDescription)")

                }
            }

        }

        CKContainer.defaultContainer().publicCloudDatabase.addOperation(operation)
    }

使用Predicate1，输出为:

Optional(John)
sucess

使用Predicate2，输出为:

couldn't fetch record error:Optional("Field \'name\' has a value type of STRING and cannot be queried using filter type LIST_CONTAINS")

同时使用 [c] 忽略大小写会导致服务器问题。

如何正确使用运算符CONTAINS？

编辑:我现在仔细查看了文档，发现 CONTAINS 只能与 SELF 一起使用。这意味着所有字符串字段都将用于搜索。有没有更好的办法？

Answer 1

这是一个异常，如下所示:

With one exception, the CONTAINS operator can be used only to test list membership. The exception is when you use it to perform full-text searches in conjunction with the self key path. The self key path causes the server to look in searchable string-based fields for the specified token string. For example, a predicate string of @"self contains 'blue'" searches for the word “blue” in all fields marked for inclusion in full-text searches. You cannot use the self key path to search in fields whose type is not a string.

因此，您可以使用“self”而不是“%K”来搜索字符串字段的子文本。

For the full document written by Apple