thread 1: EXC_BAD_ACCESS (code=1, address = 0x70 error on appDelegate when clicking save or click back

Question

I get the following error message thread 1: EXC_BAD_ACCESS (code=1, address = 0x70 when I am in my addCustomerViewController and either click save, which at the end of the code runs self.navigationController!.popViewControllerAnimated(true), or when I click back in the same addCustomerViewController. The line of code highlighted with the error is in my AppDelegate class and its the first line as follows

class AppDelegate: UIResponder, UIApplicationDelegate{

This is the last message I get in the debug area as well. Not sure if it is related.

2015-06-17 23:03:03.744 SalesCRM[4930:1409291] CoreData: error: Failed to call designated initializer on NSManagedObject class 'Customer' 

Here is the save function. Let me know what other code you might need to see. I am lost as to how to fix this.

@IBAction func save(sender: AnyObject) {

    let appDel:AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate

    let context:NSManagedObjectContext = appDel.managedObjectContext


    if firstName.text != "" && lastName.text != "" && phoneNumber.text != ""
    {
        let newUser = NSEntityDescription.insertNewObjectForEntityForName("Customer", inManagedObjectContext: context) as NSManagedObject
        newUser.setValue(firstName.text?.lowercaseString, forKey: "firstName")
        newUser.setValue(lastName.text?.lowercaseString, forKey: "lastName")
        newUser.setValue(phoneNumber.text, forKey: "phoneNumber")
        newUser.setValue(email.text, forKey: "email")
        newUser.setValue(notes.text, forKey: "notes")
        var name = String()
        name = lastName.text!
        print(name)
        var index = advance(name.startIndex, 0)
        print(index)
        first = String(name[index]).lowercaseString
        newUser.setValue(first, forKey: "first")

        let todaysDate:NSDate = NSDate()
        let dateFormatter:NSDateFormatter = NSDateFormatter()
        dateFormatter.dateFormat = "MM-dd-yyyy hh:mm"
        let DateInFormat:String = dateFormatter.stringFromDate(todaysDate) + ": created"
        newUser.setValue(DateInFormat, forKey: "log")          
        try! context.save()
        let request = NSFetchRequest(entityName: "Customer")
        let results = try! context.executeFetchRequest(request)
        print(results)

    }
    else
    {

        let alert = UIAlertController(title: "Error", message: "Please enter all information", preferredStyle: UIAlertControllerStyle.Alert)
        alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default, handler: nil))
        self.presentViewController(alert, animated: true, completion: nil)
    }

    self.navigationController!.popViewControllerAnimated(true)
}