How to compute with Core Data - core-data

Question

I'm trying to make a small program that keeps count of the amount of times pressed on a button. I'm using Core Data to store the information. The only problem is that I can't figure out how to compute with the information in the core data. If someone can tell me how to make a variable in the code equal to the value of the information in the Core Data I know enough.
If there is another way to compute with the Core Data I would like to know about.
import UIKit
import CoreData
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let appDelegate = UIApplication.shared.delegate as! AppDelegate
let context = appDelegate.persistentContainer.viewContext
/*let newUser = NSEntityDescription.insertNewObject(forEntityName: "Data", into: context)
newUser.setValue(number, forKey: "number")
do{
try context.save()
print("Saved")
}catch{
print("Error occured in the saving process.")
}*/
let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Data")
request.returnsObjectsAsFaults = false
do{
let results = try context.fetch(request)
if results.count > 0{
for result in results as! [NSManagedObject]{
if let number = result.value(forKey: "number") as? Double{
print("number is ", number)
result.setValue(number + 1, forKey: "number")
do{
try context.save()
}catch{
}
}
}
}
}catch{
print("Error with fetching data.")
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
var number = 0.0
}
The error it's given on the line with nummer = number += 1:
Cannot assign value of type '()' to type 'Double'
I appreciate all of your answers.

Answer 1

This has nothing to do with Core Data. This line doesn't make sense:
nummer = nummerVar += 1
The += operator increases nummerVar in place. You're assigning this to number, but the return value of the += operation is not a Double, so you can't assign it to a Double.
I'm not completely sure what you intended here. You might have meant
nummer = nummerVar + 1
Or maybe you meant
nummerVar += 1
nummer = nummerVar
Either of those are valid code, but which one you need depends on what you're trying to do.