Create a Spotlight/Alfred like window on macOS with SwiftUI

// MARK: - Floating Panel

class FloatingPanel: NSPanel {
  init(contentRect: NSRect, backing: NSWindow.BackingStoreType, defer flag: Bool) {

  // Not sure if .titled does affect anything here. Kept it because I think it might help with accessibility but I did not test that.
  super.init(contentRect: contentRect, styleMask: [.nonactivatingPanel, .titled, .resizable, .closable, .fullSizeContentView], backing: backing, defer: flag)

  // Set this if you want the panel to remember its size/position
  //        self.setFrameAutosaveName("a unique name")

  // Allow the pannel to be on top of almost all other windows
  self.isFloatingPanel = true
  self.level = .floating

  // Allow the pannel to appear in a fullscreen space
  self.collectionBehavior.insert(.fullScreenAuxiliary)

  // While we may set a title for the window, don't show it
  self.titleVisibility = .hidden
  self.titlebarAppearsTransparent = true

  // Since there is no titlebar make the window moveable by click-dragging on the background
  self.isMovableByWindowBackground = true

  // Keep the panel around after closing since I expect the user to open/close it often
  self.isReleasedWhenClosed = false

  // Activate this if you want the window to hide once it is no longer focused
  //        self.hidesOnDeactivate = true

  // Hide the traffic icons (standard close, minimize, maximize buttons)
    self.standardWindowButton(.closeButton)?.isHidden = true
    self.standardWindowButton(.miniaturizeButton)?.isHidden = true
    self.standardWindowButton(.zoomButton)?.isHidden = true
  }

  // `canBecomeKey` and `canBecomeMain` are required so that text inputs inside the panel can receive focus
  override var canBecomeKey: Bool {
    return true
  }

  override var canBecomeMain: Bool {
    return true
  }
}

class AppDelegate: NSObject, NSApplicationDelegate {

  var newEntryPanel: FloatingPanel!

  func applicationDidFinishLaunching(_ aNotification: Notification) {
      createFloatingPanel()

      // Center doesn't place it in the absolute center, see the documentation for more details
      newEntryPanel.center()

      // Shows the panel and makes it active
      newEntryPanel.orderFront(nil)
      newEntryPanel.makeKey()
  }

  func applicationWillTerminate(_ aNotification: Notification) {
      // Insert code here to tear down your application
  }

  private func createFloatingPanel() {
      // Create the SwiftUI view that provides the window contents.
      // I've opted to ignore top safe area as well, since we're hiding the traffic icons
      let contentView = ContentView()
          .edgesIgnoringSafeArea(.top)

      // Create the window and set the content view.
      newEntryPanel = FloatingPanel(contentRect: NSRect(x: 0, y: 0, width: 512, height: 80), backing: .buffered, defer: false)

      newEntryPanel.title = "Floating Panel Title"
      newEntryPanel.contentView = NSHostingView(rootView: contentView)
  }
}