GeometryReader Without Breaking Layout (SwiftUI)

GeometryReader hands you the size and frame of the space it occupies, at the cost of eating that space. Avoid it where you can; where you need it, contain it so it cannot distort the layout around it.

What the Proxy Gives You

The ViewBuilder closure receives a GeometryProxy with size, safeAreaInsets, and a frame(in:) function that converts the reader's frame into a coordinate space, including custom spaces declared with the coordinateSpace modifier.

GeometryReader { geometry in
  Text("Hello!")
    .frame(
      width: geometry.size.width,
      height: geometry.size.height
    )
}

GeometryReader places its children in the top left corner, not the center. That alone surprises most first uses; position the content yourself.

Containing It

GeometryReader expands to fill all the available space. Three ways to keep that greed from wrecking the layout:

• Full-screen use is fine as is; the reader wants all the space and you want it to have it.
• Otherwise, cap it with frame or aspectRatio so it only takes the space you assign.
• Best: put the reader inside a background or overlay of the view you want to measure. SwiftUI sizes background and overlay views to their host, so the reader reports the host's size without claiming any layout space of its own.

SomeView()
  .background(
    GeometryReader { geometry in
      Color.clear.preference(
        key: SizePreferenceKey.self,
        value: geometry.size
      )
    }
  )

When to Skip It

For drawing, use the Shape API instead. Shape.path(in rect: CGRect) already receives the available space, so a chart or custom shape needs no GeometryReader at all.