这是 Swift4.2 的,PDF 版,Language Guide 部分是带目录标签,其他部分无目录标签(你几乎不会去看的)
Swift is a fantastic way to write software, whether it’s for phones, desktops, servers, or anything else that runs code. It’s a safe, fast, and interactive programming language that combines the best in modern language thinking with wisdom from the wider Apple engineering culture and the diverse contributions from its open-source community. The compiler is optimized for performance and the language is optimized for development, without compromising on either.