get Double back from core data into text field - swift

Question

I am trying to put numbers into core data and then retrieve them back. I can already this with strings and it all works fine but trying to do it with doubles it seems to store them but not retrieve them. Below is my code. I hope someone can help, Thank you in advance if you can.
To retrive...
func getTranscriptions18CW () {
let fetchRequest: NSFetchRequest<TextInputs> = TextInputs.fetchRequest()
do {
//go get the results
let searchResults18CW = try getContext().fetch(fetchRequest)
if indexPageSum == 18 {
for trans in searchResults18CW as [NSManagedObject] {
let result = trans.value(forKey: "cWeight")
if result != nil {
CWeight.text = result! as? String
}
}
}
}catch {
print("Error with request: \(error)")
}
}
then to Save.
func getContext () -> NSManagedObjectContext {
_ = UIApplication.shared.delegate as! AppDelegate
return DataController().managedObjectContext
}
func storeTranscription18CW (pageText: Double, textFileUrlString: String) {
let context = getContext()
//retrieve the entity that we just created
let entity = NSEntityDescription.entity(forEntityName: "TextInputs", in: context)
let transc = NSManagedObject(entity: entity!, insertInto: context)
// set the entity values
if indexPageSum == 18 {
transc.setValue(pageText, forKey: "cWeight")
}
//save the object
do {
try context.save()
print("saved!")
} catch let error as NSError {
print("Could not save \(error), \(error.userInfo)")
} catch {
}
}
then another part to save.
if indexPageSum == 18 {
let CWConvert = Double(CWeight.text!)
storeTranscription18CW(pageText: (CWConvert)!, textFileUrlString: "cWeight")

Answer 1

The expression:
result! as? String
basically means "if result is of type String then return it, otherwise return nil". This works fine for Strings stored in the DB, but assigns nil to CWeight.text for anything else.
You want something like the following:
if let result = trans.value(forKey: "cWeight") {
if let str = result as? String {
CWeight.text = str
}
else {
CWeight.text = "\(result)"
}
}
This will work for the most common data types. The expression "\(result)" uses string interpolation to convert the value stored in result to an appropriate string.
You probably also want to look into generating NSManagedObject subclasses to make this easier to handle.