无法为名为的类创建映射策略（Cocoa错误134110）

Question

I am doing a manual/heavy migration in Core Data. I have data models ie myApp2.xcdatamodel and myApp3.xcdatamodel .

myApp3 has one new table (like junction table) in between two tables both of them were in TO-MANY relationship.

Moreover I have defined a NSEntityMigrationPolicy . Now when I run with this custom policy (which was particularly written for relationship and manage the data) I get this error specifically when calling migrationManager.migrateStoreFromURL

Optional("Error Domain=NSCocoaErrorDomain Code=134110 \"The operation couldn’t be completed. (Cocoa error 134110.)\" UserInfo=0x7feda0d825b0 {NSUnderlyingException=Couldn\'t create mapping policy for class named (MyTableToMyTablePolicy)}")

I have tried to look on this error but from one way or another it targets Policy class, which I have pasted below.

class MyTableToMyTablePolicy: NSEntityMigrationPolicy {

    override func createDestinationInstancesForSourceInstance(sourceInstance: NSManagedObject, entityMapping mapping: NSEntityMapping, manager: NSMigrationManager, error: NSErrorPointer) -> Bool {

        let sourceKeys:[AnyObject] = sourceInstance.entity.attributesByName.keys.array
        let sourceValues = sourceInstance.dictionaryWithValuesForKeys(sourceKeys)

        let destinationInstance:NSManagedObject = NSEntityDescription.insertNewObjectForEntityForName(mapping.destinationEntityName!, inManagedObjectContext: manager.destinationContext) as NSManagedObject

        let destinationKeys = destinationInstance.entity.attributesByName.keys.array as [AnyObject]

        if mapping.userInfo!["modelVersion"]!.integerValue == 2 {

            for key in destinationKeys {
                let value:AnyObject = sourceValues[key as String]!
                if value.hasText() {
                    destinationInstance.setValue(value, forKey: key as String)
                }
            }

        }
        else { // call the super just
            super.createDestinationInstancesForSourceInstance(sourceInstance, entityMapping: mapping, manager: manager, error: error)
        }

        manager.associateSourceInstance(sourceInstance, withDestinationInstance: destinationInstance, forEntityMapping: mapping)

        return true
    }
}

And following are the xcdatamodels myApp2 and myApp3 respectively:

UPDATED: Crash Log:

Answer 1

First,

Doing a heavy migration on iOS is a bad idea (tm). Heavy migration was not meant to be run on a device with limited CPU, limited memory and limited launch time.

Second,

You are probably only showing part of the error. Can you show the entire error stack? Usually Core Data errors contain internal errors that you can print out via accessing the -userInfo dictionary. That will give us a deeper understanding of the error.

Last,

Where is the debugger breaking at? What line is throwing the error?