Using KeychainAccess for saving UUID and store after reinstall app

[LiborZ]

Hi,

I am looking solution for have same ID for device even when user delete app and then install it again. I found that others are using keychain for this. But I've read about some problems that sometimes Keychain returns nil and the second problem could be that ID from keychain would be shared across devices and I really don't want that. I guess that when I set synchronizable to false that there shoudn't be second issue. But what about first one? Is it possible that sometimes Keychain returns nil even if there are saved data? For example link here: soffes/SAMKeychain#75 Should I combine this with NSUserDefaults? When app is launched for first time get ID from keychain and save it to NSUserDefaults for other needs. Thanks for help

[kishikawakatsumi]

I think that Keychain returns nil is very rare case.

[LiborZ]

Ok, thanks for answer. My usage of KeychainAccess:

func getUUID() -> String {
    let userDefaults = NSUserDefaults.standardUserDefaults()
    if let uuid = userDefaults.objectForKey(Constants.UserDefaults.UUID) as? String {
      return uuid
    } else {
      let keychain = Keychain(service: Constants.Keychain.Service)
      if let token = try? keychain.getString(Constants.Keychain.UUID) {
        if let tkn = token {
          userDefaults.setObject(token, forKey: Constants.UserDefaults.UUID)
          return tkn
        } else {
          return  self.generateNewUUID()
        }

      } else {
        return self.generateNewUUID()
      }
    }
  }

  func generateNewUUID() -> String {
    let userDefaults = NSUserDefaults.standardUserDefaults()
    let keychain = Keychain(service: Constants.Keychain.Service)

    let UUID = NSUUID().UUIDString
    userDefaults.setObject(UUID, forKey: Constants.UserDefaults.UUID)
    userDefaults.synchronize()
    keychain[Constants.Keychain.UUID] = UUID
    return UUID
  }

If it is okay you can close this. I am use it this way and for now without problem.

[itsjaychang]

Hi @LiborZ

Did setting the synchronizable to false help prevent the Keychain from being shared among devices through iCloud?

[LiborZ]

Nope. Is it enought to change in both methods code to:

let keychain = Keychain(service: Constants.KeyChain.Service).synchronizable(false)

or do I need to do more changes? Thanks