问题 As of Xcode 10.2, when using enums I've defined in Objective-C, but in a Swift 5 switch statement, I get the following warning, even if I've exhausted all the possible enum values. Switch covers known cases, but 'MyObjectiveCEnumName' may have additional unknown values Xcode is telling me I should fix this by Handle unknown values using "@unknown default" Why is this happening and what can I do about it? Example Objective-C enum typedef NS_ENUM(NSUInteger, CardColor) { CardColorBlack,