What is SliverAppBar in Flutter?
Why Interviewers Ask This
This tests whether you can apply Flutter knowledge to real-world scenarios. Interviewers are looking for clarity of thought and evidence that you've encountered this in production code.
Answer
SliverAppBar is a special app bar designed to work inside a CustomScrollView. It can expand when scrolled to the top and collapse as the user scrolls down, creating a collapsible header effect. Key properties: expandedHeight (height when fully expanded), flexibleSpace (content to show when expanded, often a hero image), pinned: true (keeps the collapsed bar visible), and floating: true (re-appears when scrolling up). It enables modern, polished scroll effects seen in many popular apps.
Common Mistake
A common mistake is memorizing definitions without understanding implications. When asked this question, go one level deeper — explain what happens when this concept is misused or ignored.