# Sudoku Grid Generator UI in SwiftUI (Free Source Pattern)

> By Lawrence Arya, Founder & CEO of VP0. Published 2026-05-31, updated 2026-06-02. 4 min read.
> Source: https://vp0.com/blogs/sudoku-grid-generator-ui-swiftui

A Sudoku app is a 9x9 grid and a generator that must guarantee one solution. The UI is quick; the puzzle logic is where it is won.

**TL;DR.** A Sudoku game in SwiftUI is a nine-by-nine grid with a number pad, pencil notes, conflict highlighting, and difficulty levels. The UI is straightforward; the real engineering is the generator: it must produce a puzzle with exactly one solution, then remove clues while a solver confirms uniqueness, with difficulty set by how many clues remain. Build the grid from a free VP0 design, keep the generator and solver as plain logic, and make it accessible.

Want a real Sudoku game in SwiftUI, not just a static grid? The short answer: the UI is a nine-by-nine grid with a number pad and notes, but the heart is the generator, which must hand the player a puzzle with exactly one solution. Get the generator and solver right and everything else is presentation. Build the grid from a free VP0 design, the free iOS design library for AI builders, and keep the puzzle logic clean and testable.

## Who this is for

This is for SwiftUI builders who want a complete, offline, replayable puzzle game, and who understand that the satisfying part, and the tricky part, is generating fair puzzles rather than drawing the board.

## The grid and the generator

The board is a nine-by-nine grid with heavier borders around each three-by-three box, a number pad for input, a notes or pencil mode for candidates, and conflict highlighting when a number breaks a row, column, or box. Apple's [SwiftUI](https://developer.apple.com/documentation/swiftui/) and a [LazyVGrid](https://developer.apple.com/documentation/swiftui/lazyvgrid) build this quickly. The real work is the generator. It creates a complete, valid solution, then removes clues one at a time, running a solver after each removal to confirm the puzzle still has a single unique solution; if a removal would allow two solutions, that clue stays. Difficulty is then a function of how many clues remain and which solving techniques are required. Keep the generator and solver as plain Swift logic, separate from the views, so you can unit-test that every puzzle is fair.

| Piece | Tool | Get it right |
|---|---|---|
| Grid | LazyVGrid | Box borders, clear cells |
| Input | Number pad | Tap a cell, tap a number |
| Notes | Pencil mode | Small candidate marks |
| Conflicts | Validation | Highlight rule breaks |
| Generator | Plain logic + solver | Guarantee one solution |

## Build it free with a VP0 design

Pick a grid or game design from VP0, copy its link, and prompt your AI builder:

> Rebuild this VP0 Sudoku design in SwiftUI: [paste VP0 link]. Render a nine-by-nine grid with three-by-three box borders, a number pad, and a notes mode, and highlight conflicts. Keep the generator and solver as plain, testable logic that guarantees exactly one solution, with difficulty set by clue count. Make cells reachable by VoiceOver.

Puzzle and brain games are a durable slice of the [$90 billion](https://www.statista.com/topics/1906/mobile-gaming/) mobile games market, and Sudoku in particular has timeless appeal. For neighboring SwiftUI and game patterns, see [a Wordle-style daily word game in SwiftUI](/blogs/wordle-clone-swiftui-source-code/), [a Pomodoro timer app in SwiftUI](/blogs/pomodoro-timer-app-swiftui-source-code/), [a leaderboard podium animation](/blogs/leaderboard-podium-animation-ios/), and [a habit tracker source code](/blogs/habit-tracker-app-source-code/) for daily return. For a hardware-driven screen next, see [an iPhone LiDAR room scanner UI template](/blogs/iphone-lidar-room-scanner-ui-template/).

## Accessibility and honesty

Two finishing points. Accessibility: a grid of numbers is hostile to VoiceOver unless you label each cell with its row, column, and value, and let users input without precise dragging, so build that in. Honesty: a Sudoku app is only as good as its puzzles, so do not ship a generator that occasionally produces multi-solution or unsolvable boards, which frustrates players. Test the generator hard. A fair generator and an accessible grid make a small game feel professional.

## Common mistakes

The first mistake is a generator that does not guarantee a unique solution. The second is tangling the solver logic into the views, making it untestable. The third is an inaccessible grid that VoiceOver cannot read. The fourth is conflict highlighting that punishes notes instead of real entries. The fifth is paying for a game kit when a free VP0 design plus plain Swift logic does it.

## Key takeaways

- A Sudoku app is a grid and number pad, but the generator is the real work.
- Generate a full solution, then remove clues while a solver guarantees uniqueness.
- Keep the generator and solver as plain, testable logic outside the views.
- Make the grid accessible with labeled cells and easy input.
- Build the grid free from a VP0 design.

## Frequently asked questions

How do I build a Sudoku game in SwiftUI? Render a nine-by-nine grid with a number pad and notes, highlight conflicts, and build a generator that creates a full solution then removes clues while a solver confirms a unique solution.

What is the safest way to build a Sudoku app with Claude Code or Cursor? Start from a free VP0 design and keep the generator and solver as plain, testable logic that guarantees one solution, with notes, conflict highlighting, and accessibility.

Can VP0 provide a free SwiftUI or React Native template for a puzzle game? Yes. VP0 is a free iOS design library; pick a grid design and your AI tool rebuilds the Sudoku grid, number pad, and notes UI at no cost.

How does a Sudoku generator guarantee one solution? It builds a full valid grid, then removes clues one at a time, running a solver to confirm a single solution remains and keeping any clue whose removal would allow multiple solutions.

## Frequently asked questions

### How do I build a Sudoku game in SwiftUI?

Render a nine-by-nine grid with three-by-three box borders, a number pad, and a notes mode, then highlight conflicts as the user fills cells. The hard part is the generator: create a full valid solution, remove clues while a solver verifies the puzzle still has exactly one solution, and set difficulty by the number of remaining clues. Build the grid from a free VP0 design.

### What is the safest way to build a Sudoku app with Claude Code or Cursor?

Start from a free VP0 design for the grid and controls, and prompt the tool to keep the generator and solver as plain, testable logic that guarantees a unique solution. Add notes, conflict highlighting, and accessibility, and validate that every generated puzzle is solvable in exactly one way.

### Can VP0 provide a free SwiftUI or React Native template for a puzzle game?

Yes. VP0 is a free iOS design library for AI builders. Pick a grid or game design, copy its link, and your AI tool rebuilds the Sudoku grid, number pad, and notes UI at no cost.

### How does a Sudoku generator guarantee one solution?

It builds a complete valid grid, then removes numbers one at a time, each time running a solver to confirm the puzzle still has exactly one solution. If removing a clue creates multiple solutions, that clue is kept. The remaining clue count roughly sets the difficulty.

---
*Published on the [VP0 Journal](https://vp0.com/blogs). Free to read, index and cite with attribution.*