Context

When using iOS App Preview, some apps rely on an authentication flow that redirects to a local callback URL (e.g., http://localhost:1455/auth/callback). In this scenario, the authentication browser within the simulator may display a "Squid — Zero Sized Reply" error, preventing the callback from reaching the app's local listener.

Answer

Unfortunately, bypassing the proxy for localhost in iOS App Preview is not currently supported. iOS App Preview does not support advanced network configuration, including proxy bypass rules for local addresses. As a result, authentication callbacks to localhost will not work as expected within the simulator's authentication browser.

If your app's authentication flow depends on a localhost callback URL, you will need to test this functionality outside of iOS App Preview using a physical device or an alternative testing environment that supports custom network configuration.