Implement an iOS scrollable grid with navigation
Company: Snapchat
Role: Software Engineer
Category: Software Engineering Fundamentals
Difficulty: hard
Interview Round: Onsite
You are building a small iOS prototype in Xcode (Swift). You may use **SwiftUI or UIKit**.
Implement a **scrollable square grid** of cells.
Incrementally add the following requirements:
1. **Fixed grid**
- Render a grid with a fixed number of rows/columns.
- Each cell is a square.
- Tapping a cell changes that cell’s color.
2. **Configurable dimensions + random color**
- The number of rows/columns is provided externally (e.g., initializer parameters).
- Each tap changes the tapped cell to a **random color**.
3. **Navigate to a detail screen**
- After tapping a cell, also navigate to a detail screen that displays the new color.
4. **Edit in detail and propagate back**
- On the detail screen, allow changing the color.
- When navigating back, the updated color must be reflected in the grid.
Discuss:
- Data model/state management
- How you would structure navigation
- How you would ensure cells remain square while scrolling
Quick Answer: This question evaluates a candidate's proficiency with iOS UI layout and interaction, including grid layout and maintaining square cells, state management and data propagation between views, touch handling, and navigation using mobile UI frameworks.