New Features in Swift 4
Faster, easier to use Strings that retain Unicode correctness and add support for creating, using and managing substrings
Smart key paths for type-safe, efficient, extensible key value coding for Swift types
Enhancements to creating and manipulating Dictionary and Set types
Extends support of archival and serialization to struct and enum types and enables type-safety for serializing to external formats such as JSON and plist
Enforced exclusive access to memory
