I’m creating a Swift-based Sudoku app whose primary mission is to teach people how to crack puzzles rather than simply letting them play. I already have the general UI vision; what I need now is a developer who can write the underlying Sudoku engine and weave in an engaging learning layer. Core objectives • Generate valid Sudoku boards on demand, analyse the current grid in real time and expose every classic solving technique (singles, pairs, X-Wing, etc.) through a clean API. • Provide instructional modes—contextual hints & tips —triggered by the user’s choice or by their mistakes. • Cover the whole spectrum of difficulty: beginner, easy, intermediate, tough and devious. Internally I’d like five granular levels, so please make the logic scalable. Key expectations – Swift 5+; I’m open to either UIKit or SwiftUI as long as the engine remains framework-agnostic. – Pure code solutions only (no third-party Sudoku libraries). – Well-documented public methods so I can plug in future UI screens. – Unit tests for board generation and every taught technique. Guaranteeing puzzles are solvable using logical strategies only (no guessing or brute force required for final puzzles). - Logging solving steps for guided teaching hints Teaching Hint System Implement a multi-step teaching hint framework that: • Detects solving strategies used by the solver • Records elimination logic and affected cells • Provides step-by-step logical explanations • Supports progressive hints (not auto-fill hints) Daily Puzzle System Create an offline daily puzzle system that: • Produces the same puzzle for all users each day • Uses deterministic puzzle selection for each level of difficulty and board transformations • Requires no server calls Scan / Import Support Support solving and validating externally provided boards (from OCR or manual input): • Validate board correctness • Confirm unique solution • Generate teaching hints for imported puzzles • Provide difficulty grading I have code for this currently but it needs refining as it doesnt always scan correctly so maybe an edit function is necessary? Acceptance criteria 1. A standalone Xcode workspace that builds without errors. 2. Engine correctly identifies and explains at least ten common solving strategies. 4. Hints surface within 200 ms on an iPhone 11 or later. 5. Test suite passes on every run. 6. Quote 'peanut butter' to let me know you read this whole thing. Deliverables • Engine source code + documentation • Sample view demonstrating the three learning modes • README outlining how to add new strategies or difficulty presets NO DESIGN OF THE GAME ITSELF IS NECESSARY this is purely an engine job. A basic sudoku board with numbers, hints and pencil is fine to deliver. Example of app that has this: sudoku (dot) com on the app store If this kind of algorithmic teaching challenge excites you, let’s talk and get puzzling.