What is the role of @State and @Binding in SwiftUI?

 In SwiftUI, @State and @Binding are property wrappers that manage data flow and state changes in views.

@State

@State is used to declare a source of truth for a view's state. It creates a mutable state property that can be changed within the view.

Characteristics:

• Owned by the view.
• The initial value is set by the view.
• Changes trigger view updates.

Use cases:

• Local state management.
• Simple forms.
• Toggle buttons.

Example:

struct CountNumberView: View {

    @State private var number = 0

    

    var body: some View {

        Button("Increment") {

            number += 1

        }

        Text("number: \(number)")

    }

}

@Binding

@Binding is a two-way connection between a view's property and an external source of truth.

Characteristics:

• References an external state.
• Changes update the external state.
• External changes update the view.

Use cases:

• Parent-child view communication.
• Shared state between views.
• Complex forms.

Example:

struct ChildView: View {

    @Binding var name: String

    

    var body: some View {

        TextField("Enter name", text: $name)

    }

}

struct ParentView: View {

    @State private var name = ""

    

    var body: some View {

        ChildView(name: $name)

        Text("Name: \(name)")

    }

}

Key differences

1. Ownership: @State owns the state, while @Binding references external state.
2. Direction: @State is one-way (view-only), while @Binding is two-way (view-external).
3. Updates: @State updates trigger view updates while @Binding updates trigger external state changes.