iOS Design Kit - The newest library of native iOS templates
Mobile Chat Kit - UI kits & sample apps for building in-app mobile chat
Sketch Repo - Collection of resources for anyone who uses Sketch
Ambient Design - Ambient is a mobile app design market where you can get unique mobile UI kits.
SketchApp.rocks - Index of all awesome things related to Sketch.
Sketch Plugin Course by Design+Code - Enhance your design workflow by creating a Sketch plugin