import UIKit
import CoreData

class Period1Controller: UIViewController, UITextFieldDelegate {

@IBOutlet weak var enterName: UITextField!
@IBOutlet weak var presentName: UITextView!
@IBOutlet weak var independceStatue: UITextField!
@IBOutlet weak var driverSelection: UITextField!

var entitys = [NSManagedObject]()
var nameList : [String] = []
var period1 = ""
var period1NameList = ""

override func viewDidLoad() {
    super.viewDidLoad()

}

func setValues() {
    nameList = [enterName.text!]
}

//this button is for saving the element into the core data
@IBAction func setName(sender: UIButton) {
    setValues()
    for item in nameList{
        period1 += (item + "  ")
        period1NameList += item
    }
    let context = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
    let entity = NSEntityDescription.entityForName("Entity", inManagedObjectContext: context)
    let otherEntity = NSManagedObject(entity: entity!, insertIntoManagedObjectContext: context)
    otherEntity.setValue(period1NameList, forKey: "period1Core")
    do {
        try context.save()
        print("Item Saved")
    } catch {
        print("Saved Failed")
    }
    presentName.text = period1
    enterName.text = ""
}

// this button is for taking out element from core data and randomly pick a value from the element I took out from core data
@IBAction func start(sender: UIButton) {
    setValues()
    let context = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
    let request = NSFetchRequest(entityName: "Entity")
    do {
        let results = try context.executeFetchRequest(request)
        entitys = results as! [NSManagedObject]
    } catch let error as NSError {
        print("Could not fetch \(error), \(error.userInfo)")
    }
    let otherEntity = entitys.last
    let randomIndex = Int(arc4random_uniform(UInt32(otherEntity.count)))
    driverSelection.text! = nameList[randomIndex]

}

}

我尝试从核心数据中随机选取一个元素，并将其设置为driverSelection文本字段。在我的代码中，我将coredata =处的元素设置为otherEntity。这使otherEntity成为NSmanagedObject，但由于otherEntity是NSmanagedObject，我不能使用.count方法。有没有什么方法可以让我从NSmanagedObject中随机选择一个元素？？？