Passing data between screens in Flutter - UI Render Trace

Component - Passing data between screens

This UI component shows how to send data from one screen to another in a Flutter app. When you tap a button on the first screen, it opens a second screen and passes a message to display.

Widget Tree

MaterialApp
└── Scaffold (HomeScreen)
    ├── AppBar
    └── Center
        └── ElevatedButton

MaterialApp
└── Scaffold (DetailScreen)
    ├── AppBar
    └── Center
        └── Text

The app starts with a MaterialApp widget. The HomeScreen uses a Scaffold with an AppBar and a centered ElevatedButton. When pressed, it navigates to DetailScreen, which also uses a Scaffold with an AppBar and a centered Text widget showing the passed message.

Render Trace - 5 Steps

Step 1: MaterialApp

Step 2: HomeScreen Scaffold

Step 3: ElevatedButton

Step 4: Navigator.push

Step 5: DetailScreen Scaffold

State Change - Re-render

Trigger:User taps the 'Go to Detail' button on HomeScreen.

Before

HomeScreen is visible with the button.

→

After

DetailScreen is visible showing the passed message.

Re-renders:The entire screen changes from HomeScreen to DetailScreen.

UI Quiz - 3 Questions

What happens when the button on the HomeScreen is tapped?

A The button changes its label.

B The app closes.

C The app navigates to DetailScreen and passes a message.

D Nothing happens.

Key Insight

Passing data between screens in Flutter is done by sending arguments when navigating. The Navigator widget manages screen transitions, and the receiving screen uses constructor parameters to access the data. This keeps screens loosely connected and easy to manage.