Small NSManagedObject extension to simplify fetching and creating objects.

CDHelper.swift

import Foundation
import CoreData

extension NSManagedObject {

    class var entityName: String {
        return NSStringFromClass(self).componentsSeparatedByString(".").last!
    }

    convenience init(context: NSManagedObjectContext) {
        let entityDescription = NSEntityDescription.entityForName(self.dynamicType.entityName, inManagedObjectContext: context)!
        self.init(entity: entityDescription, insertIntoManagedObjectContext: context)
    }

    class func fetchRequest(predicate: NSPredicate? = nil, sortDescriptors: [NSSortDescriptor]? = nil) -> NSFetchRequest {
        let request = NSFetchRequest(entityName: self.entityName)
        request.predicate = predicate
        request.sortDescriptors = sortDescriptors
        return request
    }

    class func allInstances(context: NSManagedObjectContext, predicate: NSPredicate? = nil, sortDescriptors: [NSSortDescriptor]? = nil) throws -> [NSManagedObject]? {
            let request = self.fetchRequest(predicate, sortDescriptors: sortDescriptors)
            return try context.executeFetchRequest(request) as? [NSManagedObject]
    }
}