tl;dr:Apple released SwiftUI last year and, "if your target platform is iOS 14, you’re now good to go with hobby projects or individual screens in SwiftUI." However, Peter wouldn't use it for production apps, citing several reasons in this post.
tl;dr:Swift runtime is now included in current and future versions of macOS, iOS, tvOS and watchOS. Also introduces reimplementation of String, enforcement of exclusive access to memory during runtime, new data types, and support for dynamically callable types.