Xcode6.3ではSwiftとObjective-Cの連携を強化するために、Objective-Cの新機能としてnullabilityアノテーションが導入されました。 In previous Xcode releases, some Apple frameworks had been specially audited so that their API would show up with proper Swift optionals. Xcode 6.3 supports this for your own code with a new Objective-C language feature: nullability annotations.Swift blog NullabilityとObjective-C Swiftの特徴の一つとして、Objective-Cのコードと透過的に