How to Fix Error Use of unresolved identifier contentsOfURL

I'm using XCode 8 to build an IOS10 app with Core Data. I've defined a DataController class as per the Core Data Programming Guide as follows:

import Foundation
import UIKit
import CoreData
class DataController: NSObject{
    var managedObjectContext: NSManagedObjectContext
    override init(){
        guard let modelURL = NSBundle.mainBundle().URLForResource("SympleApp", withExtension: "momd") else {
            fatalError("Error loading model from bundle")
        }
        guard let mom = NSManagedObjectModel(contentsOfURL, modelURL) else {
            fatalError("Error initializing mom from: \(modelURL)")
        }
        let psc = NSPersistentStoreCoordinator(managedObjectModel: mom)
        managedObjectContext = NSManagedObjectContext(concurrencyType: .MainQueueConcurrencyType)
        managedObjectContext.persistentStoreCoordinator = psc
       
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0))
        {
            let urls = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)
            let docURL = urls[urls.endIndex-1]
            let storeURL = docURL.URLByAppendingPathComponent("DataModel.sqlite")
            do {
                try psc.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: storeURL, options: nil)
            } catch {
                fatalError("Error migrating store: \(error)")
            }
        }
    }
}

Questions:

1. My build fails with error message per above. How do I resolve?

2. The Programming Guide provides great detail about the mechanics of Core Data. Is there another resource that show project structure, where to store my entities etc.?

Thanks for your help and guidance.