What is the difference between `FlowLayout` and `WrapHStack` for wrapping tag-style views in SwiftUI?

FlowLayout uses the Layout protocol (iOS 16+) — SwiftUI's official first-party layout system. You implement sizeThatFits (return required size given a proposal) and placeSubviews (position children in final bounds). It's clean, zero-boilerplate, and participates correctly in the layout system.

WrapHStack is a View, not a Layout. It measures its own width with GeometryReader and positions children manually using alignmentGuide inside a ZStack. Height is reported via a PreferenceKey two-pass trick: render → measure → resize with @State var totalHeight.

	FlowLayout	WrapHStack
Approach	Layout protocol	View + GeometryReader
Width source	Layout proposal	GeometryReader (actual rendered)
Height reporting	Returned from sizeThatFits	Measured via PreferenceKey
Works in ScrollView	❌ Unreliable	✅ Reliable
Accepts any content	✅ Yes	❌ Needs RandomAccessCollection
Spacing configurable	✅ Both axes	❌ Row spacing hardcoded
iOS version	iOS 16+	Any