Snapchat·Software Engineer·Technical Phone Screen·Intermediate

Intermediate

Jul 2026

Summary

Snapchat software engineer interview where they had me build a scrollable color grid live in Xcode. Pretty hands-on, more about getting something working than talking through theory.

Questions Asked (1)

Using SwiftUI or UIKit, build a scrollable grid of squares where the number of rows and columns are passed in as parameters. Tapping a cell should change it to a random color.

Technical Trade-offsSystem DesignAPI & Integrations

Author's notes

The parameterization part tripped me up more than I expected.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and choosing between SwiftUI and UIKit based on trade-offs like development speed, performance, and team familiarity. Outline a high-level design using a grid layout (LazyVGrid or UICollectionView) with dynamic cell generation and tap handling. Then dive into implementation details, discussing data flow, state management, and performance considerations for large grids.

Pro tip: Mention that you'd use a compositional layout with UICollectionView for UIKit or LazyVGrid for SwiftUI to efficiently handle large grids, and emphasize the importance of reusing cells to optimize memory and scrolling performance.

1. Clarify Requirements and Choose Framework

Ask about target iOS version, performance expectations, and whether SwiftUI or UIKit is preferred. Discuss trade-offs: SwiftUI for rapid development and declarative syntax, UIKit for fine-grained control and backward compatibility.

2. Design the Grid Layout

For SwiftUI, use LazyVGrid with a fixed number of columns and rows, or a nested ForEach. For UIKit, use UICollectionView with a compositional layout or flow layout, configuring item size and spacing.

3. Implement Cell Rendering and Reuse

Create a reusable cell component that displays a square with a background color. Ensure cells are dequeued/reused properly to handle large grids efficiently.

4. Handle Tap Gestures and State Updates

Add a tap gesture recognizer or button action to each cell. On tap, generate a random color and update the cell's background color, ensuring the state change is reflected in the UI.

5. Discuss Performance and Edge Cases

Talk about optimizing for large grids (e.g., lazy loading, cell reuse), handling dynamic type, accessibility, and potential memory issues. Mention testing on different device sizes.

Key Points to Mention

Trade-offs between SwiftUI and UIKit: development speed, performance, and maintainability.
Use of LazyVGrid (SwiftUI) or UICollectionView with compositional layout (UIKit) for efficient grid rendering.
Cell reuse and lazy loading to handle large numbers of rows and columns without performance degradation.
State management: using @State in SwiftUI or a data source in UIKit to track cell colors.
Random color generation: using UIColor with random RGB values or SwiftUI's Color with random components.
Accessibility considerations: ensuring cells are tappable and provide feedback, and supporting VoiceOver.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.