Unit Testing with Xcode 7 in Swift

AppCoda.com

Eerste Apple Development Center in Europa. (Dutch)

Technologium.be

3D Touch Introduction: Building a Digital Scale App and Quick Actions

AppCoda.com, also translated in Chinese.

Getting started with Apple Watch development

LearnSwift.io

Creating a Selectable Table App Using WatchKit

AppCoda.com, also translated in Chinese.

What's New in Swift 2.0: A Brief Introduction

AppCoda.com