Swift Error Handling

Priority: P0

Implementation Guidelines

Throwing Functions

• Propagate Errors: Use throws for recoverable errors.
• Do-Catch: Handle errors close to source with specific catch blocks.
• Error Types: Define custom errors as enums conforming to Error.

Result Type

• Async Alternatives: Use Result<Success, Failure> for callback-based APIs.
• Transformations: Use .map(), .flatMap() for functional composition.
• Conversion: Use .get() to convert Result to throwing.

Never Type

• Fatalisms: Use Never return type for functions that never return.
• Preconditions: fatalError(), preconditionFailure() for programmer errors.

Anti-Patterns

• Force Try: **No try!**: Use try? or do-catch.
• Silent Failures: **No try? without nil check**: Handle or log.
• String Errors: **No Error(message)**: Use typed errors.

References

• Error Types & Result