'<…> is not a valid NSFetchRequest.'

Question

I am using a custom source expression

NSExpression(format: \"FETCH(FUNCTION($manager, \\\"customFetchRequestForSourceEntityNamed:predicateString:\\\" , \\\"\\(m         


        

Answer 1

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

The signature would be -

extension NSMigrationManager {

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