Is it possible to override the default font in a SwiftUI app?

I'm building a SwiftUI app that has a custom font. There are many articles on how to do that and all of them requires that I set some kind of modifier on every single text.

This can't be real, that Apple prevents us to override the default font used by adding a text:

Text("This is a simple text, using the default global font.")

There is the built-in modifier:

Text("...")
   .font(.custom("FontName", size: 13)

There is the environment identifier, which allows to se the default text on an entire view:

.environment(\.font, Font.custom("RobotoMono-Regular", size: 14))

But dear god, why do I have to do this on every single view?

And none of the above allows me to utilize the built-in styling of:

Text("Text")
   .font(.title)

AND none of the above - or the many hacks on the internet allows changing the font in the navigation top bar or tab bar...

What am I missing here? How do I do that?

Solution

Here are a few techniques that might help:

You can set a font on a top level parent and this will be used in child views where no explicit font is specified. However, I think you need to specify the size, you can't set a generic font family:

ContentView()
    .font(.custom("AmericanTypewriter", size: 16))

To make it easier to apply different sizes, you could define some custom font styles as extensions to Font:

extension Font {
    static let customTitle = Font.custom("AmericanTypewriter", size: 28)
}

Text("hello").font(.customTitle)

Changing the font of the navigation title is not easy, but you could always show your own title instead. Then you can style it any way you like. The answer to Change NavigationStack title font, tint, and background in SwiftUI shows how this can be done (it was my answer).