Yes, you have to
Delete the storyboard file and delete the NSExtensionMainStoryboard property and add NSExtensionPrincipalClass that will be the class MessagesViewController and this your MSMessagesAppViewController.
Add to your code @objc(MessagesViewController)
In viewDidLoadMethod insert
// Get the UIKit view of your SwiftUI View
let child = UIHostingController(rootView: SwiftUIView())
self.view.addSubview(child.view)
// Set the place where your view will be displayed
let constraints = [
child.view.topAnchor.constraint(equalTo: view.topAnchor),
child.view.bottomAnchor.constraint(equalTo: view.bottomAnchor),
child.view.leadingAnchor.constraint(equalTo: view.leadingAnchor),
child.view.trailingAnchor.constraint(equalTo: view.trailingAnchor),
child.view.widthAnchor.constraint(equalTo: view.widthAnchor),
child.view.heightAnchor.constraint(equalTo: view.heightAnchor)
]
view.addConstraints(constraints)
Hope it will help you !