# matchedGeometryEffect(id:in:properties:anchor:isSource:) Defines a group of views with synchronized geometry using an identifier and namespace that you provide. ``` nonisolated func matchedGeometryEffect(id: ID, in namespace: Namespace.ID, properties: MatchedGeometryProperties = .frame, anchor: UnitPoint = .center, isSource: Bool = true) -> some View where ID : Hashable ``` ## Parameters `id` The identifier, often derived from the identifier of the data being displayed by the view. `namespace` The namespace in which defines the `id`. New namespaces are created by adding an `@Namespace` variable to a [`View`](/documentation/SwiftUI/View) type and reading its value in the view’s body method. `properties` The properties to copy from the source view. `anchor` The relative location in the view used to produce its shared position value. `isSource` True if the view should be used as the source of geometry for other views in the group. ## Return Value A new view that defines an entry in the global database of views synchronizing their geometry. ## Discussion This method sets the geometry of each view in the group from the inserted view with `isSource = true` (known as the “source” view), updating the values marked by `properties`. If inserting a view in the same transaction that another view with the same key is removed, the system will interpolate their frame rectangles in window space to make it appear that there is a single view moving from its old position to its new position. The usual transition mechanisms define how each of the two views is rendered during the transition (e.g. fade in/out, scale, etc), the `matchedGeometryEffect()` modifier only arranges for the geometry of the views to be linked, not their rendering. If the number of currently-inserted views in the group with `isSource = true` is not exactly one results are undefined, due to it not being clear which is the source view. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)