SwiftUI NavigationBar height

Question

How to get current NavigationBar height? In UIKit we could get

navigationController?.navigationBar.frame.height

but can't find anything for SwiftUI...

The approach can be the same as for TabBar in [Programmatically detect Tab Bar or TabView height in SwiftUI](https://stackoverflow.com/a/59972635/12299030) — Asperi, Feb 15 '20 at 18:56

score 22 · Accepted Answer · answered Feb 17 '20 at 09:08

Based on this post (thanks to Asperi): https://stackoverflow.com/a/59972635/12299030

struct NavBarAccessor: UIViewControllerRepresentable {
    var callback: (UINavigationBar) -> Void
    private let proxyController = ViewController()

    func makeUIViewController(context: UIViewControllerRepresentableContext<NavBarAccessor>) ->
                              UIViewController {
        proxyController.callback = callback
        return proxyController
    }

    func updateUIViewController(_ uiViewController: UIViewController, context: UIViewControllerRepresentableContext<NavBarAccessor>) {
    }

    typealias UIViewControllerType = UIViewController

    private class ViewController: UIViewController {
        var callback: (UINavigationBar) -> Void = { _ in }

        override func viewWillAppear(_ animated: Bool) {
            super.viewWillAppear(animated)
            if let navBar = self.navigationController {
                self.callback(navBar.navigationBar)
            }
        }
    }
}

And then we can call this from any View:

.background(NavBarAccessor { navBar in
      print(">> NavBar height: \(navBar.bounds.height)")
                // !! use as needed, in calculations, @State, etc.
 })

This works fine. But don't use it on the NavigationView, since navigation controller will be nil then. Also, the `typealias` in the `NavBarAccessor` can be removed. — José, Oct 20 '20 at 07:30

score 2 · Answer 2 · answered Jun 02 '21 at 22:21

Building on @yoprst 's response, rather than configure calculations and @State variables, you could also return a View to insert directly into the hierarchy:

struct NavigationBarAccessor: UIViewControllerRepresentable {
    var callback: (UINavigationBar) -> (AnyView)
    private let proxyViewController = ProxyViewController()

    func makeUIViewController(context: UIViewControllerRepresentableContext<NavigationBarAccessor>) -> UIViewController {
        self.proxyViewController.callback = callback
        return proxyViewController
    }

    func updateUIViewController(_ uiViewController: UIViewController, context: UIViewControllerRepresentableContext<NavigationBarAccessor>) {
    }

    private class ProxyViewController: UIViewController {
        var callback: ((UINavigationBar) -> AnyView)?

        override func viewWillAppear(_ animated: Bool) {
            super.viewWillAppear(animated)
            if let navigationBar = self.navigationController?.navigationBar {
                _ = self.callback?(navigationBar)
            }
        }
    }
}

Usage:

VStack {
    NavigationBarAccessor { navigationBar in
        Spacer()
            .frame(height: navigationBar.frame.height)
    }
}

a generic constraint would be more preferable rather than AnyView using — Sega-Zero, Jan 09 '22 at 19:09

l1Dan · Answer 3 · 2021-10-18T14:12:47.510

-3

Use GeometryReader, like this:

ZStack {
    GeometryReader { geometry in
        Rectangle().fill(Color.blue).frame(height: geometry.safeAreaInsets.bottom + 44.0)
    }
    Text("Content")
}
.edgesIgnoringSafeArea(.top)

edited Oct 18 '21 at 14:12

answered Oct 18 '21 at 14:04

l1Dan

9
6

SwiftUI NavigationBar height

3 Answers3