Lesson 3: Swift setup and first program: Debugging scenario

Concept Explanation

In "Swift setup and first program: Debugging scenario," you will solve a fresh problem, compare alternatives, and explain the trade-offs behind your choices. The lesson is built around a practical workflow so you can translate the concept into code that feels relevant to real development work. You will build, test, and refine a Swift solution with an emphasis on safe optionals, clear APIs, and maintainable app architecture. This standalone lesson helps you practice one concept deeply while using Swift patterns that commonly appear in iOS and macOS projects. Lesson fingerprint: swift:Swift Beginner:Swift setup and first program:beginner-swift-setup-and-first-program-3:3.

Where to Put the Code

1. Define color and position variables at the top.
2. Create shape drawing or placement logic in the middle.
3. Render output (print, canvas, SVG, or styled block) at the end.

Command Reference

• Refactor once using safe optionals, clear APIs, and maintainable app architecture.
• Run the starter solution, then verify one expected result and one edge result.
• Create a quick test input set for lesson unit 3.
• Identify where this pattern appears in realistic development work.

Step-by-step Guide

1. Write a brief note explaining what changed and why.
2. Test one normal case and one edge case.
3. Refactor for readability and maintainability using safe optionals, clear APIs, and maintainable app architecture.
4. Finish with a short checklist for correctness and clarity.
5. Compare two implementations and choose one with a clear justification.

Practice Exercises

• Rewrite the logic in a cleaner style without changing the result.
• Create a short output report that demonstrates correctness.
• Extend the solution so it fits a more realistic workflow.

Coding Challenges

• Scale the solution to a larger input set and review how it behaves.
• Apply one quality rule based on safe optionals, clear APIs, and maintainable app architecture across all code blocks.

Mini Practice Tasks

• Rename variables or functions to make their purpose clearer.
• Summarize in one line what the code is meant to solve.
• Write one quick test, or use a short manual checklist, and run it.