如何在Core Data中编写BOOL谓词？ [英] How to write a BOOL predicate in Core Data?

问题描述

我有一个 BOOL 类型的属性，我想搜索所有此属性为 YES 。

I have an attribute of type BOOL and I want to perform a search for all managed objects where this attribute is YES.

对于字符串属性，它很简单。我创建一个这样的谓词：

For string attributes it is straightforward. I create a predicate like this:

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"userName = %@", userName];

但如果我有一个名为的bool属性我想为此做一个谓词？我可以这样做吗？

But how do I do this, if I have a bool attribute called selected and I want to make a predicate for this? Could I just do something like this?

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"selected = %@", yesNumber];

或者我需要其他格式说明符，只需传递 YES ？

Or do I need other format specifiers and just pass YES?

推荐答案

来自谓词编程指南：

您指定并测试布尔值的相等性，如以下示例所示：

You specify and test for equality of Boolean values as illustrated in the following examples:

NSPredicate *newPredicate = [NSPredicate predicateWithFormat:@"anAttribute == %@", [NSNumber numberWithBool:aBool]];
NSPredicate *testForTrue = [NSPredicate predicateWithFormat:@"anAttribute == YES"];

您还可以查看谓词格式字符串语法。

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