This content was released on Jun 14 2019. The official support period is 6-months from this date.
Xcode 11 has a great new preview canvas for SwiftUI that allows you see changes in your UI as you make them - even letting you interact in live mode!
This is a companion discussion topic for the original entry at https://www.kodeco.com/3849386-swift-ui-previewing-your-ui-in-xcode