﻿NSManagedObjectContext *context = ...;
NSEntityDescription *employeeEntity = [NSEntityDescription
    entityForName:@"Employee" inManagedObjectContext:context];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:employeeEntity];
[request setRelationshipKeyPathsForPrefetching:
    [NSArray arrayWithObject:@"department"]];