# State modifiers Access storage and provide child views with configuration data. ## Overview SwiftUI provides tools for managing data in your app. For example, you can store values and objects in an environment that’s shared among the views in a view hierarchy. Any view that shares the environment — typically all the descendant views of the view that stores the item — can then access the stored item. For more information about the types that SwiftUI provides to help manage data in your app, see [Model data](/documentation/SwiftUI/Model-data). ## Topics ### Identity [`func tag(V, includeOptional: Bool) -> some View`](/documentation/SwiftUI/View/tag(_:includeOptional:)) Sets the unique tag value of this view. [`func id(ID) -> some View`](/documentation/SwiftUI/View/id(_:)) Binds a view’s identity to the given proxy value. [`func equatable() -> EquatableView`](/documentation/SwiftUI/View/equatable()) Prevents the view from updating its child view when its new value is the same as its old value. ### Environment values [`func environment(T?) -> some View`](/documentation/SwiftUI/View/environment(_:)) Places an observable object in the view’s environment. [`func environment(WritableKeyPath, V) -> some View`](/documentation/SwiftUI/View/environment(_:_:)) Sets the environment value of the specified key path to the given value. [`func environmentObject(T) -> some View`](/documentation/SwiftUI/View/environmentObject(_:)) Supplies an observable object to a view’s hierarchy. [`func transformEnvironment(WritableKeyPath, transform: (inout V) -> Void) -> some View`](/documentation/SwiftUI/View/transformEnvironment(_:transform:)) Transforms the environment value of the specified key path with the given function. ### Preferences [`func preference(key: K.Type, value: K.Value) -> some View`](/documentation/SwiftUI/View/preference(key:value:)) Sets a value for the given preference. [`func transformPreference(K.Type, (inout K.Value) -> Void) -> some View`](/documentation/SwiftUI/View/transformPreference(_:_:)) Applies a transformation to a preference value. [`func anchorPreference(key: K.Type, value: Anchor.Source, transform: (Anchor) -> K.Value) -> some View`](/documentation/SwiftUI/View/anchorPreference(key:value:transform:)) Sets a value for the specified preference key, the value is a function of a geometry value tied to the current coordinate space, allowing readers of the value to convert the geometry to their local coordinates. [`func transformAnchorPreference(key: K.Type, value: Anchor.Source, transform: (inout K.Value, Anchor) -> Void) -> some View`](/documentation/SwiftUI/View/transformAnchorPreference(key:value:transform:)) Sets a value for the specified preference key, the value is a function of the key’s current value and a geometry value tied to the current coordinate space, allowing readers of the value to convert the geometry to their local coordinates. [`func onPreferenceChange(K.Type, perform: (K.Value) -> Void) -> some View`](/documentation/SwiftUI/View/onPreferenceChange(_:perform:)) Adds an action to perform when the specified preference key’s value changes. [`func backgroundPreferenceValue(Key.Type, (Key.Value) -> T) -> some View`](/documentation/SwiftUI/View/backgroundPreferenceValue(_:_:)) Reads the specified preference value from the view, using it to produce a second view that is applied as the background of the original view. [`func backgroundPreferenceValue(K.Type, alignment: Alignment, (K.Value) -> V) -> some View`](/documentation/SwiftUI/View/backgroundPreferenceValue(_:alignment:_:)) Reads the specified preference value from the view, using it to produce a second view that is applied as the background of the original view. [`func overlayPreferenceValue(Key.Type, (Key.Value) -> T) -> some View`](/documentation/SwiftUI/View/overlayPreferenceValue(_:_:)) Reads the specified preference value from the view, using it to produce a second view that is applied as an overlay to the original view. [`func overlayPreferenceValue(K.Type, alignment: Alignment, (K.Value) -> V) -> some View`](/documentation/SwiftUI/View/overlayPreferenceValue(_:alignment:_:)) Reads the specified preference value from the view, using it to produce a second view that is applied as an overlay to the original view. ### Default storage [`func defaultAppStorage(UserDefaults) -> some View`](/documentation/SwiftUI/View/defaultAppStorage(_:)) The default store used by `AppStorage` contained within the view. ### Configuring a model [`func modelContext(ModelContext) -> some View`](/documentation/SwiftUI/View/modelContext(_:)) Sets the model context in this view’s environment. [`func modelContainer(ModelContainer) -> some View`](/documentation/SwiftUI/View/modelContainer(_:)) Sets the model container and associated model context in this view’s environment. [`func modelContainer(for:inMemory:isAutosaveEnabled:isUndoEnabled:onSetup:)`](/documentation/SwiftUI/View/modelContainer(for:inMemory:isAutosaveEnabled:isUndoEnabled:onSetup:)) Sets the model container in this view for storing the provided model type, creating a new container if necessary, and also sets a model context for that container in this view’s environment. --- 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)