[FEATURE] Swift generator

[alexgavrisco]

Why do we need this improvement?

Since Swift is the default language for iOS/macOS/etc, being able to generate API types from schemas is a significant dev experience improvement.
Adding support for Swift closes the parity loop for mobile stacks, reduces manual model writing, and prevents drift between platforms.

How will this change help?

• Generates Swift DTOs that are immediately usable with JSONDecoder/JSONEncoder, minimizing boilerplate.
• Improves cross-platform consistency and accelerates adoption of Modelina in mobile apps.
• Encourages schema-first development by making Swift a first-class target alongside existing generators.

Screenshots

No response

How could it be implemented/designed?

• Follow the existing “new generator” template (structure, presets, tests, examples).
• Output struct models conforming to Codable, plus string/int enum types. Use CodingKey when property names differ from JSON keys.

Open question: handling untyped object (free-form/dynamic) and undecidable unions: Codable is strongly typed and doesn’t natively support “any” values. Options include:

• Using a well-known type-erased value (e.g., AnyCodable) behind a generator option.
• Emitting a custom JSONValue enum (string/number/bool/array/object/null).
• Providing a strict mode that forbids dynamic values (fail fast) to enforce fully typed schemas.

I'd prefer to ship a strict mode that fails fast for types not supported OOTB by Codable, and add later a mode that uses a companion library with some container types (Apple's OpenAPI Generator works in a similar way).
Please let me know your thoughts.

🚧 Breaking changes

No

👀 Have you checked for similar open issues?

• I checked and didn't find a similar issue

🏢 Have you read the Contributing Guidelines?

• I have read the Contributing Guidelines

Are you willing to work on this issue?

Yes I am willing to submit a PR!

[github-actions]

Welcome to AsyncAPI. Thanks a lot for reporting your first issue. Please check out our contributors guide and the instructions about a basic recommended setup useful for opening a pull request.
Keep in mind there are also other channels you can use to interact with AsyncAPI community. For more details check out this issue.

[jonaslagoni]

@alexgavrisco never need permission to work on new generators!

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity 😴

It will be closed in 120 days if no further activity occurs. To unstale this issue, add a comment with a detailed explanation.

There can be many reasons why some specific issue has no activity. The most probable cause is lack of time, not lack of interest. AsyncAPI Initiative is a Linux Foundation project not owned by a single for-profit company. It is a community-driven initiative ruled under open governance model.

Let us figure out together how to push this issue forward. Connect with us through one of many communication channels we established here.

Thank you for your patience ❤️