How Change Background Color If Using Navigationview in Swiftui

How To Set NavigationView Background Colour in SwiftUI

It is same as UINavigationBar. But since there is no direct api yet, you can change it using appearance:

UINavigationBar.appearance().backgroundColor = .orange
UINavigationBar.appearance().tintColor = .green
UINavigationBar.appearance().barTintColor = .yellow
UINavigationBar.appearance().titleTextAttributes = [.foregroundColor: UIColor.red]
UINavigationBar.appearance().largeTitleTextAttributes = [.foregroundColor: UIColor.red]

You should put this somewhere that you sure the compiler reads like inside the init() method.

Note that some of these will not work below Xcode 11 beta 5.

How to change background color of the NavigationView in SwiftUI?

First look at this result:

View hierarchy

As you can see, you can set the color of each element in the View hierarchy like this:

struct ContentView: View {
    
    init(){
        UINavigationBar.appearance().backgroundColor = .green 
        //For other NavigationBar changes, look here:(https://stackoverflow.com/a/57509555/5623035)
    }

    var body: some View {
        ZStack {
            Color.yellow
            NavigationView {
                ZStack {
                    Color.blue
                    Text("Some text")
                }
            }.background(Color.red)
        }
        // iOS 16 - No need for tweaking the appearance
        /* .toolbarBackground(.green, in: .navigationBar) */
    }
}

And the first one is window:

window.backgroundColor = .magenta

The issue you faced is we can not remove the background color of SwiftUI's HostingViewController (yet), so you can't see the navigationView (What you called) through the views hierarchy. You should wait for the API or try to fake the navigation view (not recommended).

SwiftUI background color of the screen with NavigationView

Updated:
with putting Color as ignoresSafeArea!

import SwiftUI

struct ContentView: View {
    
    var body: some View {
        
        NavigationView {
            
            ZStack {
                
                Color
                    .red
                    .ignoresSafeArea()     // <<: Here
                
                Color
                    .yellow
                    .cornerRadius(20)
                    .padding()
                
                
            }.navigationTitle("Today")
            
            .navigationBarItems(leading: Text("some texts"))
        }
        
    }
}

Sample Image

SwiftUI NavigationView background color

You could introduce a custom ViewModifier as described here.

Working example:

import SwiftUI

struct NavigationBarModifier: ViewModifier {
    var backgroundColor: UIColor?

    init(backgroundColor: UIColor?) {
        self.backgroundColor = backgroundColor
    }

    func body(content: Content) -> some View {
        ZStack{
            content
            VStack {
                GeometryReader { geometry in
                    Color(self.backgroundColor ?? .clear)
                        .frame(height: geometry.safeAreaInsets.top)
                        .edgesIgnoringSafeArea(.top)
                    Spacer()
                }
            }
        }
    }
}

extension View {

    func navigationBarColor(_ backgroundColor: UIColor?) -> some View {
        self.modifier(NavigationBarModifier(backgroundColor: backgroundColor))
    }

}

struct MyContentView: View {
    var body: some View {
        NavigationView {
            ScrollView {
                VStack(spacing: 8) {
                    Text("One")
                        .roundedContainer()
                    Text("Two")
                        .roundedContainer()
                }
                .padding()
            }
            .background(Color(.systemGroupedBackground))
            .navigationBarTitle("Summary", displayMode: .large)
            .navigationBarColor(.systemGroupedBackground)
        }
    }
}

SwiftUI changing navigation bar background color for inline navigationBarTitleDisplayMode

I think I have what you want. It is VERY touchy... It is a hack, and not terribly robust, so take as is...

I got it to work by having your modifier return a clear NavBar, and then the solution from this answer works for you. I even added a ScrollView to ThirdView() to make sure that scrolling under didn't affect in. Also note, you lose all of the other built in effects of the bar like translucency, etc.

Edit: I went over the code. The .navigationViewStyle was in the wrong spot. It likes to be outside of the NavigaionView(), where everything else needs to be inside. Also, I removed the part of the code setting the bar color in FirstView() as it was redundant and ugly. I hadn't meant to leave that in there.

struct NavigationBarModifier: ViewModifier {

    var backgroundColor: UIColor?
    var titleColor: UIColor?
    

    init(backgroundColor: Color, titleColor: UIColor?) {
        self.backgroundColor = UIColor(backgroundColor)
        
        let coloredAppearance = UINavigationBarAppearance()
        coloredAppearance.configureWithTransparentBackground()
        coloredAppearance.backgroundColor = .clear // The key is here. Change the actual bar to clear.
        coloredAppearance.titleTextAttributes = [.foregroundColor: titleColor ?? .white]
        coloredAppearance.largeTitleTextAttributes = [.foregroundColor: titleColor ?? .white]
        coloredAppearance.shadowColor = .clear
        
        UINavigationBar.appearance().standardAppearance = coloredAppearance
        UINavigationBar.appearance().compactAppearance = coloredAppearance
        UINavigationBar.appearance().scrollEdgeAppearance = coloredAppearance
        UINavigationBar.appearance().tintColor = titleColor
    }

    func body(content: Content) -> some View {
        ZStack{
            content
            VStack {
                GeometryReader { geometry in
                    Color(self.backgroundColor ?? .clear)
                        .frame(height: geometry.safeAreaInsets.top)
                        .edgesIgnoringSafeArea(.top)
                    Spacer()
                }
            }
        }
    }
}

extension View {
    func navigationBarColor(backgroundColor: Color, titleColor: UIColor?) -> some View {
        self.modifier(NavigationBarModifier(backgroundColor: backgroundColor, titleColor: titleColor))
    }
}

struct FirstView: View {
    @State private var selection: String? = nil
    
    var body: some View {
         NavigationView {
            GeometryReader { _ in
                VStack {
                    Text("This is the first view")
                    
                    NavigationLink(destination: SecondView(), tag: "SecondView", selection: $selection) {
                        EmptyView()
                    }
                    Button(action: {
                        self.selection = "SecondView"
                        print("Go to second view")
                    }) {
                        Text("Go to second view")
                    }
                }
                .navigationTitle("First")
                .navigationBarTitleDisplayMode(.inline)
                .navigationBarColor(backgroundColor: .red, titleColor: .black)
            }
        }
        .navigationViewStyle(StackNavigationViewStyle())
    }
}
    

struct SecondView: View {
    @State private var selection: String? = nil
    
    var body: some View {
        VStack {
            Text("This is the second view")
            
            NavigationLink(destination: ThirdView(), tag: "ThirdView", selection: $selection) {
                EmptyView()
            }
            Button(action: {
                self.selection = "ThirdView"
                print("Go to third view")
            }) {
                Text("Go to third view")
            }
        }
        .navigationTitle("Second")
        .navigationBarTitleDisplayMode(.inline)
        .navigationBarColor(backgroundColor: .blue, titleColor: .black)
    }
}

struct ThirdView: View {
    var body: some View {
        ScrollView {
            ForEach(0..<50) { _ in
                Text("This is the third view")
            }
        }
        .navigationTitle("Third")
        .navigationBarTitleDisplayMode(.inline)
        .navigationBarColor(backgroundColor: .green, titleColor: .black)
    }
}