There are a lot of active Twitter users that use Swift; in many cases posts will be marked with the #swift hashtag, and can be found at http://twitter.com/search?q=%23swift. Popular users that the author follows include (in alphabetical Twitter handle name):
@AirspeedSwift:This twitter has a good selection of tweets and retweets of Swift-related subjects@ChrisEidhof: This is author of the Functional Swift book and@objcio@CodeWithChris: This twitter is a collection of tutorials on iOS programming@CodingInSwift:This twitter contains cross-posts by a collection of Swift resources@CompileSwift: This twitter contains posts on Swift@cwagdev: Chris Wagner writes some of the iOS tutorials with Ray Wenderlich@FunctionalSwift: This is a selection of functional snippets, along with a Functional Swift book@LucasDerraugh: This is the creator of video tutorials on YouTube@NatashaTheRobot:This twitter contains a great summary of what's happening, along with newsletters and cross references@nnnnnnnn: Nate Cook, who reviewed an earlier version of this book and provides the Swifter list just mentioned@PracticalSwift: This is a good collection of blog posts talking about the Swift language@rwenderlich: Ray Wenderlich has many posts relating to iOS development; a wealth of information and more recently Swift topics as well@SketchyTech: This is a collection of blog posts on Swift@SwiftCastTV: These are video tutorials of Swift@SwiftEssentials: This is the twitter feed for this book@SwiftLDN: This Twitter posts Swift meetups based in London, also invites great Swift talks and presenters
In addition to the Swift-focused Twitter users, there are a number of other Cocoa (Objective-C) developers who blog regularly on topics relating to the iOS and OS X platforms. Given that any Objective-C framework can be integrated into a Swift app (and vice versa), quite often, there will be useful information from reading these posts:
@Cocoanetics: Oliver Drobnik writes about iOS and provides training@CocoaPods: CocoaPods is a dependency management system for Objective-C frameworks (pods) and is being extended into the Swift domain@Mattt: Mattt Thompson writes about many iOS subjects, is the author of the AFNetworking and AlamoFire networking libraries, and who moved to Apple to write the Swift package manager@MikeAbdullah:@MikeAsh: Mike Ash knows everything there is to know, and what he doesn't know, he finds out@MZarra: Marcus S. Zarra has written a lot about Core Data and synching@NSHipster: This is a collection of assembled iOS and Cocoa posts that are organised by Mattt Thompson@objcio: This is a monthly publication on Objective-C topics with some Swift@PerlMunger: Matt Long posts about Swift, Cocoa, and iOS
The reviewers of this book included:
@AnilVrgs: Anil Varghese@Ant_Bello: Antonio Bello@ArvidGerstmann: Arvid Gerstmann@jiaaro: James Robert@nnnnnnnn: Nate Cook
The author's personal and book twitter accounts are:
@AlBlueis the author's twitter account@SwiftEssentialsis the book's twitter account
Meetups such as @SwiftLdn keep a track of interesting Swift writers in a Twitter list at https://twitter.com/SwiftLDN/lists/swift-writers/members, which may have more up-to-date recommendations than this section, as well as the Ray Wenderlich team at https://twitter.com/rwenderlich/lists/raywenderlich-com-team/members.