InterfaceViewController

The InterfaceViewController struct helps you to use UIKit UIViewController or its derived class in project using SwiftUI. InterfaceViewController is a type that represents part of your app’s user interface using UIKit and provides modifiers that you use to configure views.

You create custom views by declaring types that conform to the View protocol. Implement the required View/body-swift.property computed property to provide the content for your custom view. Then you can present your UIKit ViewController View by using InterfaceViewController(MyViewController()) , as follows.

struct MyView: View {
    var body: some View {
        InterfaceViewController(MyViewController())
    }
}

The View protocol provides a large set of modifiers, defined as protocol methods with default implementations, that you use to position and configure views in the layout of your app. Modifiers typically work by wrapping the view instance on which you call them in another view with the specified characteristics. For example, adding the View/opacity(_:) modifier to a interface view returns a new view with some amount of transparency:

InterfaceViewController(MyViewController())
    .opacity(0.5) // Display partially transparent interface view.

It is recommended to use ZStack with InterfaceViewController , as follows.

ZStack {
    InterfaceViewController(MyViewController())
    MySwiftUIView()
}

Use an InterfaceViewController instance to create and manage a doc://com.apple.documentation/documentation/UIKit/UIViewController object in your SwiftUI interface. Use this struct 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 InterfaceViewController 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 NSViewControllerRepresentable/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.

  • The type of view controller to present.

  • A closure helps you finish some special things like work to be done in UIKit interface.

Initialization

  • Creates an InterfaceViewController instance from the specified parameters.

MakeUIViewController

  • Creates the view controller object and configures its initial state.

    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 UIViewControllerRepresentable/updateUIViewController(_:context:) method.

UpdateUIViewController

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

    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.

  • A return type for function makeCoordinator.

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

    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 UIViewControllerRepresentable/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.