User Default Values Changing to Previous Values after some time - Swift - ios

Question

Please don't mark my question duplicate.
Gone through the following links and tried what they mentioned but no luck.
UserDefaults in IOS 10 is sometimes showing old value
User Default Values Changing to Previous Values Seemingly Randomly - Swift
UserDefaults in IOS 10 is sometimes showing old value
When a user login into the app I am storing some values from login API response in user defaults.
UserDefaults.standard.set(val, forKey: "XYZ")
When the user log out of the app I'm deleting user defaults.
logOutAlert.addAction(UIAlertAction(title: "Yes", style: .default, handler: { (action: UIAlertAction!) in
// Mark:- Function that remove user defaults data
self.resetDefaults()
BackgroundTask().stopUpdate()
let loginVC = self.storyboard?.instantiateViewController(withIdentifier: "LoginVC") as! LoginVC
self.showAlert(title: Constant.projectTitle, message: "Successfully loged out.")
let appDel:AppDelegate = UIApplication.shared.delegate as! AppDelegate
appDel.window?.rootViewController = loginVC
}))
// Reset userdefaults
func resetDefaults() {
//let domain = Bundle.main.bundleIdentifier!
//UserDefaults.standard.removePersistentDomain(forName: domain)
UserDefaults.standard.dictionaryRepresentation().keys.forEach(UserDefaults.standard.removeObject(forKey:))
// let defaults = UserDefaults.standard
// let dictionary = defaults.dictionaryRepresentation()
// dictionary.keys.forEach { key in
// defaults.removeObject(forKey: key)
// }
}
Commented lines are the ways I tried to solve a problem.
Please go through following scenario
Install app
Log in (user A)
Log out (user A)
Log in (user B)
Kill app from memory (not uninstall)
Wait for around 20 mins.
Relaunch app.
Issue - user A's user defaults data restored automatically.
Thanks in advance. Any help surely appreciated, sorry for my English.

Answer 1

Try this maybe it could work .. Use this removeobject on the logout button Action method .
let defaults = UserDefaults.standard
defaults.synchronize()
UserDefaults.standard.removeObject(forKey: "email")
UserDefaults.standard.removeObject(forKey: "name")
UserDefaults.standard.removeObject(forKey: "userid")
UserDefaults.standard.removeObject(forKey: "mobno")
UserDefaults.standard.removeObject(forKey: "profileimage")
UserDefaults.standard.removeObject(forKey: "iphoneid")

Answer 2

You might want to try another way around:
//Set an empty dictionary for the main domain, instead of removing the old one
guard let domain = Bundle.main.bundleIdentifier else { return }
let emptyDomain = [String : Any]()
UserDefaults.standard.setPersistentDomain(emptyDomain, forName: domain)
I have a theory that the removePersistentDomainForName method is buggy, and it deletes the old domain, but fails to instantiate an empty domain dictionary after the deletion, so it just keeps the old one for that case.

Answer 3

I think the problem is that you're trying to remove all keys from UserDefaults.standard without any filter. UserDefaults.standard contains more keys than you think and some of them are managed by iOS itself.
In order to identify the keys you manage you should put a prefix or (example: "MYAPP_username") and remove only these keys.
Here is the code:
let keys = UserDefaults.standard.dictionaryRepresentation().keys.filter { return $0.starts(with: "MYAPP_") }
for key in keys {
UserDefaults.standard.removeObject(forKey: key)
}
This should work and hope it does ;-)

Answer 4

I think this solution would be helpful in your situation. This will clean all user userdefaults and give you something like the app is just installed.
I would recommend storing all user related sensitive data in keychain.
Try
NSUserDefaults.standardUserDefaults().removePersistentDomainForName(NSBundle.mainBundle().bundleIdentifier!)
NSUserDefaults.standardUserDefaults().synchronize()
It is best to add synchronize if your target version is iOS 11 or lower, which will help to write to disc immediately.

Answer 5

Add Observer For changes in Defaults
Debug if you are actually changing from your code unintensionaly using below approach.
In your AppDelegate Add below code:
UserDefaults.standard.addObserver(self, forKeyPath: "XYZ", options: NSKeyValueObservingOptions.new, context: nil)
And observe using method
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
// Check when It's getting trigged.
}
Apple's Synchronize method
If you are working this Asynchronous tasks you may have to try calling this method UserDefaults.standard.synchronize().
Check what value it returns. If it is false, (I have never seen this method returning false) You can conclude something internal things are blocking you from saving to disk.
func synchronize() -> Bool
Return value
true if the data was saved successfully to disk, otherwise false.