: Like a regular default , it matches any value not explicitly covered by other cases.
: It cannot be merged with other cases (e.g., you cannot write case .first, @unknown default: ). Comparison: default vs @unknown default default @unknown default Catch-all Future-proofing Warning if known cases missing Yes Behavior on new cases Triggers warning to update code Common Issues What's the deal with "@unknown default" - Swift Forums unknowndefault
This report focuses on , a feature introduced in Swift 5 to handle "non-frozen" enumerations—enums where new cases might be added in the future without breaking existing code. Core Functionality : Like a regular default , it matches