Way of handling important data temporarily in swift

Hello! I have been making an app where a user is able to create an account, as well as provide other important data like their name, address, weight, etc.

When it comes to managing the data between view controllers, what do you recommend as a way to save the data for account creation purposes temporarily such as stage 1 (enter your username) and stage 2 (enter your password)(as moving into the next view controller through a segue removes all data?)

As I am using firebase to process the data (not store it) I considered using user defaults with a temporary system where after 5 minutes, all data is wiped under a "session timeout", however I am skeptical of this. What are your thoughts as I am new to this?

Way of handling important data temporarily in swift
 
 
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