The callback execution thread is not consistent

[lionhylra]

The callback execution thread is not consistent

[Widcket]

Hi @lionhylra, thanks for raising this.

I'm unable to reproduce this issue; both error and success results are being delivered on the main thread. Which specific error are you triggering?

[lionhylra]

I did web auth on a client who's authentication method is POST. This will trigger .pkceNotAllowed error, but the callback was executed on a background queue. As I mentioned in the issue description, it was this line of code:

Auth0.swift/Auth0/OAuth2Grant.swift

Line 84 in d621132

return callback(.failure(WebAuthError(code: .pkceNotAllowed)))

[Widcket]

Thanks for the clarification. The long-standing convention on Apple plaftorms is to execute callbacks in whatever queue the last operation was executed. Following this, as you mentioned, we don't specify in our docs that the callbacks will be called in any specific queue. However, I agree that given the need to deal with UI updates shortly after in case of error, calling it on the main thread would improve the developer experience.

I don't have an ETA for this, but I'll leave this open for future planning and reference.

[Widcket]

Hi, given that:

• Addressing this on the current major could lead to unnecessarily dispatching to the main queue twice (once by Auth0.swift, and then again by the current application code)
• Even though always delivering the result on the main thread would improve DX, it's a nice-to-have
• The current behavior follows a long-standing convention

We'll defer this improvement to the next (future) major. I've already made a note of this, so I'll go ahead and close this issue.

Thanks for bringing this to our attention!