Fix for the transparent/gray navigation bar in iOS 15

FixNavigationBarColor.swift

// For UIKit project
override func viewDidLoad() {
    super.viewDidLoad()
    self.title = "Demo App"
    self.navigationController?.navigationBar.isTranslucent = false
    self.navigationController?.navigationBar.tintColor = .white
    self.navigationController?.navigationBar.barTintColor = .red
    if #available(iOS 13.0, *) {
        let appearance = UINavigationBarAppearance()
        appearance.titleTextAttributes = [NSAttributedString.Key.foregroundColor: UIColor.white]
        appearance.configureWithOpaqueBackground()
        appearance.backgroundColor = .red
        self.navigationController?.navigationBar.standardAppearance = appearance
        self.navigationController?.navigationBar.scrollEdgeAppearance = appearance
    }
    self.navigationController?.navigationBar.titleTextAttributes = [NSAttributedString.Key.foregroundColor: UIColor.white]
}


// For SwiftUI project
init() {
    let appearance = UINavigationBarAppearance()
    appearance.titleTextAttributes = [.foregroundColor: UIColor.white]
    appearance.configureWithOpaqueBackground()
    appearance.backgroundColor = .red
    UINavigationBar.appearance().standardAppearance = appearance
    UINavigationBar.appearance().scrollEdgeAppearance = appearance
    UINavigationBar.appearance().isTranslucent = false
}