There are a number of blogs that cover Swift and related technologies. Here are a selection that you may be interested in:
https://developer.apple.com/swift/blog/ is the official Apple Swift blog
http://airspeedvelocity.net is the blog for
@AirspeedSwift
http://alblue.bandlem.com/Tag/swift/ is the author's blog on Swift
http://mikeabdullah.net is Mike Abdullah's blog
http://mikeash.com writes the Friday Q&A series on all things iOS and OS X
http://natecook.com/blog/tags/swift/ is Nate Cook's blog on Swift
http://nshipster.com is the blog for
@NSHipster
http://objc.io is the blog for
@objcio
http://practicalswift.com is collected by
@PracticalSwift
http://sketchytech.blogspot.co.uk is a collected blog of Swift articles by
@SketychTech
http://swiftessentials.org is the companion site for this book, along with the repository at https://github.com/alblue/com.packtpub.swift.essentials/
http://swiftnews.curated.co is collected by
@NatashaTheRobot
http://www.cimgf.com presents a collection of topics on Cocoa, by Marcus S Zarra and others
http://www.raywenderlich.com has a collection of tutorials about iOS development, including both Cocoa and Swift