[SwiftUI] How to set custom font to NavigationBarTitle

NavigationView {
    VStack { ... }
        // ↓ set custom font
        .navigationTitleFont(font: UIFont.custom.extraBold(ofSize: 20))
}

import SwiftUI
import Introspect

public struct NavigationTitleFontModifier: ViewModifier {
    public var font: UIFont

    public func body(content: Content) -> some View {
        content
            .introspectNavigationController {
                $0.navigationBar.titleTextAttributes = [.font:font]
            }
    }
}

extension UIFont {
    public struct custom {
        static func extraBold(ofSize size: CGFloat) -> UIFont {
            return UIFont(name: "BoldCustomFontName", size: size) ?? UIFont.systemFont(ofSize: size, weight: .bold)
        }
    }
}

public extension View {
    func navigationTitleFont(font: UIFont) -> some View {
        self.modifier(NavigationTitleFontModifier(font: font))
    }
}