无法使用Swift中的NSPredicate查询日期 [英] Unable to query for date using NSPredicate in Swift

问题描述

我正在尝试在特定日期之后提取日期。我的谓词如下：

I'm trying to make a fetch for dates later than a specific date. My predicate is as follows:

NSPredicate(format: "date > \(currentDate)")

当我执行获取请求时，我遇到了异常：

When I executed the fetch request I caught an exception:

'Unable to parse the format string "date > 2015-07-08 03:00:00 +0000"'

我以为我可以这样做一个查询。我做错了什么？

I thought I could make a query like that. What am I doing wrong?

推荐答案

NSPredicate（格式：_：）获取格式字符串和参数列表，但是您传递的是一个简单的字符串。这不起作用，因为这个初始化器不只是对参数调用 stringWithFormat：，但实际上在构建谓词时会查看参数的类型信息。

NSPredicate(format:_:) takes a format string and a list of arguments, but you're passing a simple string. This doesn't work, since this initializer doesn't just call stringWithFormat: on the parameters, but actually looks at the arguments' type information as it's building the predicate.

您可以通过将日期作为参数传递来使用该初始化程序：

You can use that initializer by passing the date as an argument:

let datePredicate = NSPredicate(format: "date > %@", currentDate)

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