In Screens for iOS 4.8.4, we made the “One-tap User Password” feature better! Henceforth, it shall now be known as “Hold to Send Password”. This feature is super handy when you need to type your Mac user password and don’t want to bring the keyboard up and type it like an animal.
Simply tap and hold the new Actions button 
on the scrollable toolbar and after a short delay, Screens will type your password and even hit return for you. Lift your finger to cancel the operation.
The Actions button also still works as usual. Simply tap once to bring the actions menu (Disconnect, Send Clipboard, etc.)
Hold to Send Password is especially useful when the macOS login window appears right after connecting.
Update: By the way, this feature is also available in Screens for macOS:
