RealmSwift number of existing object is always 4, at start of program - swift

Question

I am using RealmSwift to create a PIN code screen for an app. I have a manager class that has a few functions, including checkForExistingPin() which is intended to be used to check whether a pin exists (as the name suggests).
When I create an instance of the manager class and call the checkForExistingPin() function, it always tells me that there are 4 (It prints: "Optional(4)"), even though I have not created a pin yet.
Can anyone explain why this might be doing this and how I might get the correct output from the code?
Here is the class:
import Foundation
import RealmSwift
class pinCode: Object {
#objc dynamic var pin = ""
}
protocol pinCodeManager {
func checkForExistingPin() -> Bool
func enterNewPin(newPin:String)
func checkPin(pin:String) -> Bool
}
class manager:pinCodeManager {
let realm = try! Realm()
func checkForExistingPin() -> Bool {
let existingCode = realm.objects(pinCode.self).first?.pin
print("\n\nNumber of existing PINs: ", existingCode?.count as Any, "\n\n") // Number of existing PINs: Optional(4)
if existingCode?.count == 0 {
return false
}
else {
return true
}
}
func enterNewPin(newPin:String) {
if checkForExistingPin() {
let oldCode = realm.objects(pinCode.self).first
try! realm.write {
oldCode!.pin = newPin
}
}
let newPinObject = pinCode()
newPinObject.pin = newPin
realm.add(newPinObject)
}
func checkPin(pin:String) -> Bool {
if checkForExistingPin() {
print ("Realm object first: ", realm.objects(pinCode.self).first?.pin as Any)
if pin == realm.objects(pinCode.self).first?.pin {
print ("Pin Correct")
return true
}
else {
print ("Pin Incorrect")
return false
}
}
print ("No existing pin")
return false
}
}
And here is the relevant code snippet of the ViewController:
class InitialViewController: UIViewController {
let myPin = pinCode()
let myManager = manager()
let realm = try! Realm()
#IBAction func NewUserButton(_ sender: Any) {
print("No existing PINs: ", self.myManager.checkForExistingPin())
}
The output is : Number of existing PINs: Optional(4)

Answer 1

You must have created a pinCode object (or multiple of them). "Optional(4) doesn't mean you have created 4 pins. You are counting String. It means that the object you retrieved has a 4 digit pin. If you haven't created any pinCode object, you should get nil. Or if you have created one without assigning a pin, you should get 0.
I recommend your looking at your realm file. You should be able to print out its location this way:
print(Realm.Configuration.defaultConfiguration.fileURL!)
You can then open the file with Realm Studio and verify what is in there.

Answer 2

You have a few things going on here:
Although this is not really in the scope of the question, here's a tip for the future. Your types' names should be capitalized (following CamelCase standard), as per Swift API Design Guidelines. Thus, your pinCodes and manager classes and pinCodeManager protocol should be called PinCode, Manager and PinCodeManager respectively.
Assuming you renamed your types and as other users pointed out, you're not counting instances of PinCode. You're counting the length of the pin member of PinCode class. Refactoring your checkForExistingPin() function:
func checkForExistingPin() -> Bool {
return realm.objects(pinCode.self).count > 0
}
In your enterNewPin(newPin:) function, in the case you already have a PinCode object stored, note that you are actually updating the old PinCode and adding a new one with the same pin. For instance, if you previously have a PinCode object stored with pin=1234. After calling enterNewPin(newPin: "5678") you will have two such objects stored with the pin=5678. You might want to refactor that as well:
func enterNewPin(newPin:String) {
if checkForExistingPin() {
let oldCode = realm.objects(pinCode.self).first
try! realm.write {
oldCode!.pin = newPin
}
} else {
let newPinObject = pinCode()
newPinObject.pin = newPin
try! realm.write {
realm.add(newPinObject)
}
}
}
Before trying to do any debugging in your app. I recommend you first uninstalling and then reinstalling the app wherever you running (simulator or actual device). If things keep behaving weird, that's probably something related with your configuration if you're overriding the default one (i.e. I noticed that you just used try! Realm() for retrieving a Realm, but you might have overridden Realm.Configuration.defaultConfiguration somewhere else).
Hope that helps!