SwiftUI

• SwiftUI

  • UIViewControllerRepresentable

  • Environment

    • environment(_:_:)

    • EnvironmentKey

    • EnvironmentValues

    • @Environment

    • @EnvironmentObject

    • environmentObject(_:)

  • viewBuilder?

UIViewControllerRepresentable

A view that represents a UIKit view controller.

Declaration:

protocol UIViewControllerRepresentable : View where Self.Body == Never

Overview:

Use a UIViewControllerRepresentable instance to create and manage a UIViewController object in your SwiftUI interface.

Adopt this protocol in one of your app’s custom instances, and use its methods to create, update, and tear down your view controller. The creation and update processes parallel the behavior of SwiftUI views, and you use them to configure your view controller with your app’s current state information. Use the teardown process to remove your view controller cleanly from your SwiftUI.

For example, you might use the teardown process to notify other objects that the view controller is disappearing.

To add your view controller into your SwiftUI interface, create your UIViewControllerRepresentable instance and add it to your SwiftUI interface. The system calls the methods of your custom instance at appropriate times.

The system doesn’t automatically communicate changes occurring within your view controller to other parts of your SwiftUI interface. When you want your view controller to coordinate with other SwiftUI views, you must provide a Coordinator instance to facilitate those interactions.

For example, you use a coordinator to forward target-action and delegate messages from your view controller to any SwiftUI views.

Topics:

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• makeUIViewController(context:)

  Creates the view controller object and configures its initial state.

  Declaration:

  func makeUIViewController(context: Self.Context) -> Self.UIViewControllerType

  Discussion:

  You must implement this method and use it to create your view controller object. Create the view controller using your app’s current data and contents of the context parameter. The system calls this method only once, when it creates your view controller for the first time. For all subsequent updates, the system calls the updateUIViewController(_:context:) method.

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• updateUIViewController(_:context:)

  Updates the state of the specified view controller with new information from SwiftUI.

  Declaration:

  func updateUIViewController(_ uiViewController: Self.UIViewControllerType, context: Self.Context)

  Discussion:

  When the state of your app changes, SwiftUI updates the portions of your interface affected by those changes. SwiftUI calls this method for any changes affecting the corresponding AppKit view controller.

  Use this method to update the configuration of your view controller to match the new state information provided in the context parameter.

• makeCoordinator()

  Creates the custom instance that you use to communicate changes from your view controller to other parts of your SwiftUI interface.

  Declaration:

  func makeCoordinator() -> Self.Coordinator

  Discussion:

  Implement this method if changes to your view controller might affect other parts of your app. In your implementation, create a custom Swift instance that can communicate with other parts of your interface.

  For example, you might provide an instance that binds its variables to SwiftUI properties, causing the two to remain synchronized. If your view controller doesn’t interact with other parts of your app, providing a coordinator is unnecessary.

  SwiftUI calls this method before calling the makeUIViewController(context:) method. The system provides your coordinator either directly or as part of a context structure when calling the other methods of your representable instance.

Environment

environment(_:_:)

• environment(_:_:)

(View) Sets the environment value of the specified key path to the given value.

Declaration:

func environment<V>(_ keyPath: WritableKeyPath<EnvironmentValues, V>, _ value: V) -> some View

EnvironmentKey

EnvironmentValues

@Environment

@EnvironmentObject

environmentObject(_:)

viewBuilder?