NSPredicate核心数据 [英] NSPredicate Core Data

问题描述

核心中的 LIKE [c]％@ 与 = [c]％@ 之间有何区别data NSPredicate ？我想搜索一个应该完全匹配接收器的字符串。
例如：

What is the exact difference between LIKE [c]%@ and = [c]%@ in core data NSPredicate? I want to search for a string that should exactly match the receiver. Example :

NSArray *arrayNames = [context fetchObjectsForEntityName:NSStringFromClass([PatientFamilyMember class])
      withSortColumn:nil withSortDescending:FALSE
      withPredicate:@"patientID = %@ && firstName=[c]%@ && relationship=[c]%@ && lastName=[c]%@",
      self.pfm.patientID, firstName, relationship, lastName];

这可行，但我还不明白使用 LIKE [c] 和 = [c]％@。

This works but I have not understood the difference between using LIKE [c] and = [c]%@.

推荐答案

在一个谓词中 LIKE 和 = 之间的区别是 LIKE 允许？和 * 作为通配符，其中？匹配1个字符， * 匹配0个或多个字符。

The difference between LIKE and = in a predicate is that LIKE allows ? and * as wildcard characters, where ? matches 1 character and * matches 0 or more characters.

两者 LIKE可以使用 [c] 修改和 = 以指定不区分大小写。

Both LIKE and = can be modified with [c] to specify case insensitivity.

示例：假设您有对象名称

Example: Assume that you have objects with names

"Mark", "mark", "Mike", "mike", "M*"

b
$ b

Both

[NSPredicate predicateWithFormat:@"name = %@", @"Mark"];
[NSPredicate predicateWithFormat:@"name LIKE %@", @"Mark"];

找到Mark，以及

[NSPredicate predicateWithFormat:@"name =[c] %@", @"Mark"];
[NSPredicate predicateWithFormat:@"name LIKE[c] %@", @"Mark"];

找到Mark和mark。但只有 LIKE 运算符可以与通配符一起使用，例如

find "Mark" and "mark". But only the LIKE operator can be used with wildcards, e.g.

[NSPredicate predicateWithFormat:@"name LIKE[c] %@", @"M*"];

找到Mark，mark，Mike，mike ，但

finds "Mark", "mark", "Mike", "mike" and "M*", but

[NSPredicate predicateWithFormat:@"name ==[c] %@", @"M*"];

只找到M *。

查看有关详细信息，请参见谓词编程指南中的字符串比较。

See String Comparisons in the "Predicate Programming Guide" for more information.

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