See this recent Collector for ArcGIS post “What’s new in Collector for ArcGIS January 2020“

You now have the ability to snap lines

 

Snapping Setting in Collector for iOS 20.1.0

 

 

 

 

 

 

 

Included in the 20.1.0 release for iOS:

  • Snapping to existing features
  • Update form entries for multiple features simultaneously
  • Reuse field entries between forms
  • Scan a code to sign in
  • View local tracks created using Tracker for ArcGIS

Feature Snapping

One of the top most requested enhancements you’ve asked for is feature snapping and we’ve added it in this release. You can snap to existing point features or vertices of lines and polygons when using the map to create new features or when updating the location of existing ones.