Preliminary SwiftUI support

For now it will simply add a `UIHostingController` `view` to the `contentView`.

I commented out calls needed for proper view controller containment because it doesn’t play well with my `UINavigationController`.

Author: rivera-ernesto

Sources/ContainerController/ContainerController.swift

@@ -7,6 +7,7 @@
 //
 
 import UIKit
+import SwiftUI
 
 open class ContainerController: NSObject {
 
@@ -24,6 +25,8 @@ open class ContainerController: NSObject {
 
     public var footerView: UIView?
 
+    public var hostingController: UIHostingController<AnyView>?
+    
     // MARK: Layout
 
     public var layout: ContainerLayout = ContainerLayout()
@@ -451,6 +454,29 @@ open class ContainerController: NSObject {
         calculationViews()
     }
 
+    // MARK: - Add SwiftUI View
+    
+    public func removeSwiftUIView() {
+//        self.hostingController?.willMove(toParent: nil)
+        self.hostingController?.view.removeFromSuperview()
+//        self.hostingController?.removeFromParent()
+        self.hostingController = nil
+    }
+    
+    public func add<V: View>(swiftUIView: V) {
+        guard let contentView = self.view.contentView else {
+            return
+        }
+        removeSwiftUIView()
+        let hostingController = UIHostingController(rootView: AnyView(swiftUIView))
+        self.hostingController = hostingController
+//        self.controller?.addChild(hostingController)
+        hostingController.view.frame = contentView.bounds
+        hostingController.view.autoresizingMask = [.flexibleWidth, .flexibleBottomMargin]
+        contentView.addSubview(hostingController.view)
+//        hostingController.didMove(toParent: self.controller)
+    }
+    
     // MARK: - Pan Gesture
 
     @objc private func handlePan(_ gesture: UIPanGestureRecognizer) {