state property swift memo

what is @state property

Overview

SwiftUI manages the storage of any property you declare as a state. When the state value changes, the view invalidates its appearance and recomputes the body. Use the state as the single source of truth for a given view.

A State instance isn’t the value itself; it’s a means of reading and mutating the value. To access a state’s underlying value, use its value property.

Only access a state property from inside the view’s body (or from functions called by it). For this reason, you should declare your state properties as private, to prevent clients of your view from accessing it.

You can get a binding from a state with the `binding` property, or by using the `$` prefix operator.

@Environment

Environment

A dynamic view property that reads a value from the view’s environment.

EnvironmentObject

A dynamic view property that uses a bindable object supplied by an ancestor view to invalidate the current view whenever the bindable object changes.