Beyond the Basics: A Developer's Guide to Crafting Custom Bottom Sheets

Have you ever noticed how some apps just feel better than others? A big part of that seamless experience often comes down to small, thoughtful UI elements like bottom sheets. They slide up gracefully, present options without yanking you away from your task, and just make everything feel connected. But when the built-in options fall short, you need to go custom. Let's talk about how to build custom bottom sheets that are functional, beautiful, and feel like a natural extension of your app.

So, what exactly is a bottom sheet? In simple terms, it's an overlay that slides up from the bottom of your screen to show extra content or options . Think of it as a temporary sidekick to your main view. You see them everywhere—Google Drive uses them for file actions, Spotify for player controls, and countless apps for menus, filters, and details . Their power lies in progressive disclosure: they show you more when you need it, without forcing you to navigate away and lose your place .

Why Go Custom When the Default Exists?

Most platforms offer a default bottom sheet component. In Android's Jetpack Compose, you have ModalBottomSheet . In SwiftUI, developers often build their own using views and gestures . But the "one-size-fits-all" approach rarely fits ambitious designs. Here's where the default solutions often hit a wall, based on real-world development challenges:

• Limited States: Need more than just collapsed and expanded? For a complex feature, the team at Turo needed three distinct states (collapsed, partially expanded, and fully expanded) to guide users through airport parking, which the standard component couldn't handle .

• Rigid Behavior: Want the sheet's height or available states to change dynamically based on user interaction or content? Static default implementations can't adapt on the fly .

• Inconsistent Experience: If you're building a cross-platform app, you'll notice Android and iOS handle bottom sheets differently out of the box (like backdrop dimming and dismissal gestures). Creating a custom solution lets you unify this experience across platforms .

The Anatomy of a Great Custom Bottom Sheet

Building your own means you control every aspect. Here are the key components you need to architect, drawing from established patterns and common pitfalls:

• State Management: This is the brain. You need a robust system (like a SheetState class in Compose or a @State variable in SwiftUI ) to track whether the sheet is hidden, partially visible, or fully expanded. For advanced cases, this state should be configurable and even changeable during use .

• Gesture Handling: This is the feel. A smooth drag-to-dismiss gesture is non-negotiable . You'll also need to manage nested scrolling—so users can scroll a list inside the sheet without accidentally closing it .

• Layout & Animation: This is the look. The sheet needs to calculate its position, often with tools like AnchoredDraggable in Compose or offset modifiers in SwiftUI . Smooth animations for opening, closing, and between states are crucial for polish.

• Lifecycle & Dismissal: This is the etiquette. A proper custom bottom sheet must clean up after itself. Crucially, it should respect the platform's back button or back gesture for dismissal, as users expect this . Providing a clear, accessible close button is also a major usability win .

Real-World Blueprint: A Kotlin Implementation

Let's get concrete. Say you're building an Android app and need a reusable, customizable dialog. Here's a high-level look at a Kotlin implementation, inspired by practical guides :

1. Extend BottomSheetDialogFragment: This gives you a foundation to work with.

2. Create a Data Class: Define a BottomSheetContent parcelable data class to neatly pass in titles, messages, and other content .

3. Inflate a Custom Layout: Design your sheet's UI in an XML file with TextViews, Buttons, etc. .

4. Manage the Dialog: In your fragment, inflate the layout, bind the data from your data class to the views, and set up click listeners for buttons (like "Dismiss") .

5. Style It: Use styles and shape drawables to set rounded corners, background color, and overlay effects to match your app's theme .

This pattern separates your data, logic, and presentation, making the component clean and maintainable.

UX Golden Rules: Don't Annoy Your Users

A powerful custom component is worthless if it frustrates users. Here are critical rules to follow, underscored by usability research :

• Never, Ever Stack Them: Opening a bottom sheet from within another bottom sheet is a usability nightmare. It breaks navigation and leaves users lost. Use normal navigation for flows .

• Keep Interactions Short: Bottom sheets are for quick actions, filters, or details—not for reading long articles or filling out complex forms. If the interaction will be lengthy, take the user to a full screen .

• Design for One-Handed Use: Place key actions, especially dismiss buttons, within easy thumb reach on large screens .

• Lead with Value: Your copy should be benefit-oriented. "Get 20% Off Now" performs better than a vague "Learn More" .

• Make Dismissal Obvious: Always provide a visual close button (like an "X") in addition to swipe-down gestures. Not all users know the gesture, and it's essential for accessibility .

The Accessibility Checklist

Speaking of accessibility, a custom component must be built for everyone. Here’s a quick checklist :

• Close Button: Must have a sufficient tap target, high color contrast, and a proper label (e.g., "Close" not just "X") for screen readers.

• Flexible Height: Ensure the sheet can expand or scroll to accommodate larger system font sizes.

• Clear Contrast: There must be clear visual separation between the sheet and the dimmed background, especially in dark mode.

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The Strategic Advantage

Why invest time in a custom solution? Because in 2025, bottom sheets are strategic engagement tools. Studies show they can achieve 25-30% higher engagement than traditional modals because they're less intrusive . Companies use them for:

• High-impact announcements like new feature launches (e.g., a credit card in a finance app) .

• Contextual upselling (e.g., a cart add-on suggestion in a delivery app) .

• Progressive feature discovery, teaching users about functionality right when they might need it .

Building your own gives you the flexibility to create these tailored, high-conversion experiences.

Final Thoughts

Building a custom bottom sheet is more than a coding exercise—it's a commitment to a superior user experience. It starts with recognizing the limitations of off-the-shelf components and having the craftsmanship to build something better. By focusing on smooth interaction, clear state management, and unwavering respect for usability and accessibility guidelines, you transform a simple UI pattern into a seamless bridge between your app and your user.

The next time you slide up a beautifully integrated panel in your favorite app, you'll appreciate the thought and code that went into making it feel effortless. Now, you have the blueprint to build that feeling into your own projects.