Revolutionizing Scrolling Experiences with Flutter’s Slivers

Revolutionizing Scrolling Experiences with Flutter’s Slivers

When developing engaging mobile apps, one crucial aspect is how users interact with and navigate through content. Traditional UI components offer a basic scrolling experience, but as apps become more complex, so too must our approach to scrolling. Enter Flutter’s slivers—a powerful feature designed to enhance the scrolling experience beyond the capabilities of standard widgets.

Traditional Approach: Using ListView and Column

Scenario: A Screen app that has ListView, a header, and a footer in a single scrollable view. Implementation (Before Slivers).

Traditional Approach Code

Multi View Scroll with Traditional Approach:  code
Output:

Traditional Approach

Read More: A guide on Optimising and Improving your Flutter app Memory performance by Using Flutter Dev Tools 

The Limitations of Standard UI Components

Traditional widgets in Flutter, such as Container, Column, and ListView, offer a straightforward approach to building layouts. However, they come with limitations:

• Fixed Layouts: Standard widgets have fixed layouts that don’t adapt dynamically as the user scrolls. This means that the appearance of these widgets remains static, making it challenging to create smooth, interactive experiences.
• Separated Scrolling Elements: In many cases, scrolling elements are treated separately from the content, leading to less fluid transitions. For example, app bars that need to hide or expand with scrolling require additional logic and can be cumbersome to implement.
• Efficiency Issues: When you need to scroll through both a list and a grid together, using a ListView or other traditional methods can become inefficient, particularly with large datasets.
• Performance Issues: The ListView and GridView are set to NeverScrollableScrollPhysics and shrinkWrap: true, which means they build all items at once. This can lead to performance bottlenecks with larger data sets.
• Limited Flexibility: Combining different types of scrollable content (e.g., lists and headers) in a single scrollable view requires intricate management and may not support complex interactions easily.

Introducing Slivers

Slivers in Flutter are designed to overcome these limitations by providing a more dynamic and interactive scrolling experience. Here’s how they stand out:

• Dynamic Behaviour: Slivers can adjust their size, position, and behavior as the user scrolls, allowing for complex animations and transitions. This means that app bars can automatically collapse or expand, creating a more polished and seamless visual effect.
• Seamless Integration: By integrating seamlessly with scrolling, slivers create a more immersive user experience. For instance, you can have a custom app bar that adjusts its appearance based on the scroll position, adding a layer of sophistication to your app’s interface.
  Efficient Scrolling: Slivers are particularly useful for efficiently handling large numbers of children. They lazily build items as they scroll into view, which significantly improves performance and reduces memory usage.

Sliver-Based Approach

Scenario: A Screen app that has ListView, header, and a footer in a single scrollable view (Same scenario which we have implemented with the Traditional Approach), Implementation with Sliver.

Sliver Approach

Multi-View Scroll with Sliver:  code

Output:

Sliver Muti View Scrolling

Read More: Is Flutter a good option to consider for your next cross platform app development?

How to Use Slivers

To harness the power of slivers, you’ll need to utilize the CustomScrollView widget. This widget acts as a container for slivers, allowing you to create custom scrollable areas tailored to your needs. Here’s a brief overview of how to get started:

• Wrap Your Slivers: All sliver components should be placed inside a CustomScrollView. This widget allows you to combine multiple slivers to build your desired scrollable area.
• Combine Slivers: You can create complex scrolling experiences by combining different types of slivers. For instance, you might use a SliverList to display a list of items and a SliverGrid for a grid of items—all within the same CustomScrollView.
• Create Custom Scroll Views: By placing a SliverList inside a CustomScrollView, you can replicate the behavior of a ListView but with the added flexibility of slivers. This approach is more efficient and provides greater control over how content is displayed and scrolled.

Types of Slivers

Flutter provides several types of slivers:

1. SliverAppBar
The SliverAppBar widget is a versatile tool for creating app bars that can expand and contract as the user scrolls. It offers a variety of behaviours to enhance the user experience:

Floating: The floating property allows the app bar to reappear as soon as the user scrolls up, providing quick access to the app bar without needing to scroll all the way back to the top. You can see this in action here.
Pinned: With the pinned property, the app bar remains visible at the top of the screen even when the user scrolls down. This ensures that the app bar is always accessible. Check out the pinned  behaviour here.
Snap: Combining with floating, the snap property makes the app bar quickly reappear when scrolling up, but not when scrolling down. This behaviour ensures a responsive and fluid interface. See how snapping works here.

2. SliverList and SliverGrid

SliverList and SliverGrid are ideal for displaying lists and grids of data efficiently:

  SliverList:  This widget is used for creating a scrollable list of widgets. It supports lazy loading, which means only the visible items are rendered, improving performance for large lists.
   SliverGrid:  Similar to SliverList, but for grid layouts. It provides a way to create grid-based scrollable views with customizable cross-axis and main-axis extent.

3. SliverToBoxAdapter
The SliverToBoxAdapter widget allows you to insert non-scrollable content into a CustomScrollView. This is useful for placing static elements, like titles or headers, among scrollable slivers.

Full Code:
💻 GitHub: Repository

Sliver Full Example

Conclusion

Flutter’s slivers offer a transformative way to enhance scrolling experiences in mobile apps. By providing dynamic, interactive, and efficient scrolling capabilities, slivers allow developers to create responsive and engaging user interfaces. Whether you’re building complex animations or managing large datasets, slivers simplify the development process and elevate the user experience. Embrace the power of slivers and transform the way your app handles scrolling.

We at TO THE NEW, help your business build web and hybrid applications for Android/IOS mobile devices with native UI/UX experience and performance. Contact us for more.