IOS APP Code Review and Refactor Some Logic Like Login and Refresh Token + Error Handling -- 2

I Need Some Help On My app
I have already done API Linking in My app and It Working fine. but Some Time Slow or lagging

Able To Remotely Work On My MAC PC With Anydesk or Team Viewer

some points I Need Help
1. Login Logic With Refresh Token
2. Receiving notifications and showing on the Screen
3. Error Handling and if Any Error show Popup Alert
4. Refactor and simplify App Code

App UI. = Swift UI
Language = Swift 5.