Replacing NSCoder with Swift's Codable

[Vaidios]

• All new/changed/fixed functionality is covered by tests (or N/A)
• I have added documentation for all new/changed functionality (or N/A)

📋 Changes

• Replaced occurrences of NSKeyedUnarchiver/NSKeyedArchiver with JSONDecoder/JSONEncoder
• Added encode function to Credentials type

📎 References

It doesn't seem like usage of this API is required in this context. Credentials type doesn't use polymorphism, which could be only handled by NSKeyedUnarchiver.

Thanks to these changes my code now properly runs inside a SPM package

Please let me know if there is something that I don't understand :)

https://forums.swift.org/t/should-i-stick-with-codable-or-switch-back-to-nscoding/61604
#862

🎯 Testing

This is not a breaking change, these code paths are covered by unit tests

[theolampert]

@Vaidios I know that this error was already not being surfaced here, so this is not a comment on your PR but more this process in general. If an NSCoder failure is the cause of #862 there is an argument to be made that the problem would have been easier to debug had this function either throw here and bubbled the error up or have the .noCredentials error provide a more descriptive message. What are your thoughts @desusai7 ?

[Vaidios]

I totally agree, it would be much easier to find a root cause if that error would be propagated.
Maybe we should throw an error such as 'credentialsParsingFailure' instead of non-descriptive 'noCredentials'.

PS. For the time being, I will remove that do-catch with print to be optional try, just as before

[Vaidios]

@theolampert sorry for tagging you here, I was just wondering if there is any button to ask for the review from maintainers and I clicked it without thinking much about it :E

[desusai7]

Hi @Vaidios,

Thank you for raising a PR to address this, we will look into it and get back to you !

[Vaidios]

Hey @desusai7, are there any updates on this?

[shusuke0812]

Hello @desusai7

We are encountering the same issue which gets "No credentials were found in the store." message.
Could you please provide any updates on when this issue might be resolved? Thank you.

[Widcket]

Hi everyone,

We cannot accept this PR because JSONDecoder cannot read credentials encoded with NSKeyedArchiver. This means all the users of all Auth0 customers using this SDK would be logged out after updating the app and would have to log in again.

This is precisely the reason why the existing NSKeyedUnarchiver/NSKeyedArchiver-based solution was left as-is during the development of Auth0.swift v2.

@shusuke0812 please see #862 (comment) for a way to log the underlying Keychain error.