https://developer.apple.com/swift/blog/: This is the official Apple Swift blog

http://airspeedvelocity.net: This is the blog for @AirspeedSwift

http://alblue.bandlem.com/Tag/swift/: This is the author's blog on Swift

http://mikeabdullah.net: This is Mike Abdullah's blog

http://mikeash.com: Here, you can find the Friday Q&A series on all things iOS and OSX

http://natecook.com/blog/tags/swift/: This is Nate Cook's blog on Swift

http://nshipster.com: This is the blog for @NSHipster

http://objc.io: This is the blog for @objcio

http://practicalswift.com: This is collected by @PracticalSwift

http://sketchytech.blogspot.co.uk: This is a collected blog of Swift articles by @SketychTech

http://swiftnews.curated.co: This is collected by @NatashaTheRobot

http://www.cimgf.com: This presents a collection of topics on Cocoa, by Marcus S Zarra and others

http://www.raywenderlich.com: This has a collection of tutorials about iOS development, including both Cocoa and Swift