macOS Menubar popover appearing in the wrong place on launch

I have a macOS menubar application and I want it to display the popover after the app has launched. The problem I'm having is that, while it does display the popover, it places it in the bottom-left corner of the screen instead of directly beneath the menubar icon.

Is there a way to make it place the popover in the correct location automatically?

Here is my code:

import Foundation
import Cocoa
import SwiftUI

class AppDelegate: NSObject, NSApplicationDelegate {
    var window: NSWindow!
    var statusBarItem: NSStatusItem!
    let popover = NSPopover()
    
    func applicationDidFinishLaunching(_ aNotification: Notification) {
        let statusBar = NSStatusBar.system
        let iconName = UserDefaults.standard.string(forKey: "selectedIcon") ?? "Color"
        statusBarItem = statusBar.statusItem(withLength: NSStatusItem.squareLength)
        statusBarItem.button?.image = NSImage(named: iconName)
        statusBarItem.button?.image?.size = NSSize(width: 18, height: 18)
        
        let contentView = ContentView()
        
        popover.behavior = .transient
        popover.contentViewController = NSHostingController(rootView: contentView)
        
        statusBarItem.button?.action = #selector(togglePopover(_:))
        statusBarItem.button?.target = self
        
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
            self.statusBarItem.button?.window?.layoutIfNeeded()
            self.statusBarItem.button?.performClick(nil)
        }
    }
    
    @objc func togglePopover(_ sender: AnyObject?) {
        if let button = self.statusBarItem.button {
            if popover.isShown {
                popover.performClose(sender)
            } else {
                popover.show(relativeTo: button.bounds, of: button, preferredEdge: NSRectEdge.minY)
            }
        }
    }
}

For it to get placed correctly, you must set the contentSize on the NSPopover. And, apparently wait slightly longer than the delay you've set. For example, this works:

let contentSize: CGSize = .init(width: 200, height: 300) // <-- Here

@main
class AppDelegate: NSObject, NSApplicationDelegate {
    var window: NSWindow!
    var statusBarItem: NSStatusItem!
    let popover = NSPopover()
    
    func applicationDidFinishLaunching(_ aNotification: Notification) {
        let statusBar = NSStatusBar.system
        statusBarItem = statusBar.statusItem(withLength: NSStatusItem.squareLength)
        statusBarItem.button?.image = NSImage(systemSymbolName: "pencil", accessibilityDescription: nil)
        statusBarItem.button?.image?.size = NSSize(width: 18, height: 18)
        
        let contentView = ContentView()
        
        popover.behavior = .transient
        popover.contentViewController = NSHostingController(rootView: contentView)
        popover.contentSize = contentSize // <-- Here
        
        statusBarItem.menu = nil
        statusBarItem.button?.action = #selector(togglePopover(_:))
        statusBarItem.button?.target = self
        
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { // <-- Here
            self.statusBarItem.button?.window?.layoutIfNeeded()
            self.statusBarItem.button?.performClick(nil)
        }
    }
    
    @objc func togglePopover(_ sender: NSStatusBarButton?) {
        if let button = self.statusBarItem.button {
            if popover.isShown {
                popover.performClose(sender)
            } else {
                popover.show(relativeTo: sender!.bounds, of: button, preferredEdge: NSRectEdge.minY)
            }
        }
    }
}

struct ContentView: View {
    var body: some View {
        Text("Hello, world")
            .frame(width: contentSize.width, height: contentSize.height) // <-- Here
    }
}

You could also dynamically read the size of the SwiftUI view and set the content size based on that. See https://www.fivestars.blog/articles/swiftui-share-layout-information/ for example.