The HIG update is the practical counterpart to the Liquid Glass announcement — it tells you what to actually build. New material guidance covers how to apply translucency correctly, when to let the system supply the glass effect versus when to customize it, and how to handle contrast and legibility against blurred backgrounds. Icon specs now explicitly address light, dark, and tinted variants as first-class requirements, not afterthoughts. The App Review Guidelines and Developer Program License Agreement were also updated June 8 to reflect new Liquid Glass and Apple Intelligence feature categories. Worth reading both before submitting apps targeting iOS 27 or macOS Golden Gate — guideline gaps that were previously informal are now codified.