本文介绍了'< ...>不是有效的NSFetchRequest."的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

我正在使用自定义的源表达式

I am using a custom source expression

NSExpression(format: "FETCH(FUNCTION($manager, \"customFetchRequestForSourceEntityNamed:predicateString:\" , \"\(mapping.sourceEntityName!)\", \"TRUEPREDICATE\"), $manager.sourceContext, NO)") 

用于映射模型.

提取通常在自定义方法中执行,但是异常'< ...>不是有效的NSFetchRequest.'稍后会在 NSMigrationManager.migrateStore()方法内抛出.

The fetch is being executed normally within the custom method, but exception '<...> is not a valid NSFetchRequest.' is thrown somewhere later inside the NSMigrationManager.migrateStore() method.

有任何线索吗?

推荐答案

此方法的预期结果类型为 NSFetchRequest ,而不是获取的返回内容.

The expected result type of this method is NSFetchRequest, not what the fetch returns.

签名应该是-

extension NSMigrationManager {

    @objc func customFetchRequest(forSourceEntityNamed entityName: String, predicateString: String) -> NSFetchRequest<NSFetchRequestResult> {

这篇关于'&lt; ...&gt;不是有效的NSFetchRequest."的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!

10-11 00:37