翻译自：https://docs.swift.org/swift-book/LanguageGuide/Enumerations.html

翻译自：https://docs.swift.org/swift-book/LanguageGuide/TypeCasting.html

翻译自：https://docs.swift.org/swift-book/LanguageGuide/ClassesAndStructures.html

翻译自：https://docs.swift.org/swift-book/LanguageGuide/Inheritance.html

翻译自：https://docs.swift.org/swift-book/LanguageGuide/AutomaticReferenceCounting.html

翻译自：https://docs.swift.org/swift-book/LanguageGuide/AccessControl.html

翻译自：https://docs.swift.org/swift-book/LanguageGuide/Generics.html

翻译自：https://docs.swift.org/swift-book/LanguageGuide/ErrorHandling.html

翻译自：https://docs.swift.org/swift-book/LanguageGuide/CollectionTypes.html

翻译自：https://docs.swift.org/swift-book/LanguageGuide/AdvancedOperators.html