I’d like a simple iOS app in Objective-C that lets me turn on a personal VPN with one tap. The main screen should have a large “Connect” button, and I should be able to choose a server by country from a list (e.g., US, UK, Germany). Please store my login securely (use the Keychain) and use the system’s VPN capabilities to start the tunnel. While connected, show a clear status (“Connected/Disconnected”) and the IP address assigned by the VPN server. Provide the overall app structure and sample code for the UI, credential handling, and the VPN setup.