These are my personal favorites 😊 in no particular order
Swift by Sundell
Allrounder and nice balance between Swift programming techniques, language features and architectural patterns.
Weekly articles about Swift + iOS programming, language features, architectural patterns and more.
Allrounder and nice focus on Swift.
Swift with Majid
My latest must-watch blog related to SwiftUI development.
Yet Another Swift Blog
His blog post about Xcode Source Editor Extension was super helpful and probably the best source of information (along with NSHipster).
The SwiftUI Lab
Lately not much updates but those in-depth articles are the best on SwiftUI and their MacApp "A Companion for SwiftUI" beats Apple's documentation by miles!
Ramblings of Peter Steinberger
No particular focus but those in-depth articles illustrating perfectly the analytical process of a good root cause analysis.