Now that you have had a good refresher of the core language features and the memory model, we can continue our journey with the Standard Library and the Foundation Framework.
The Standard Library is responsible for bringing high-level features, and it provides powerful implementations for common data types, such as strings and numbers. Along with these basic types, it implements efficient storage and algorithms for common data structures, such as arrays, dictionaries, and sets. Finally, it exposes a trove of protocols that can help to reduce boilerplate in your own implementations, as well as implement common features like Equatable, OptionSet, or Collection.
Foundation is at the core of all Apple SDKs, providing a base layer for your programs in Swift, including (but not limited to) networking, file management, persistence...