Context
NB: The question does NOT pertain to iOS
I have a Mac app that shows an NSPopover. The content of that popover is an NSHostingView that displays a simple SwiftUI view:
struct PopoverView: View
{
#State private var buttonWidthScale: CGFloat = 1.0
var body: some View
{
Button {
...
} label: {
RoundedRectangle(cornerRadius: 6.0)
.fill(.blue)
.scaleEffect(CGSize(width: buttonWidthScale, height: 1))
.animation(.easeInOut(duration: 2.5).repeatForever(), value: buttonWidthScale)
.onAppear {
buttonWidthScale = 0.96
}
}
}
}
The goal is to have a blue rectangle that very subtly "pulses" its width. The above works just fine to do that.
The Problem
I assumed (quite stupidly) that SwiftUI is smart enough to suspend the animation when the popover closes and the view is no longer on screen. That is not the case. Once the view appears for the first time, the app will now consume 5-6% CPU forever. The app correctly uses 0% CPU before this NSPopover appears for the first time and the animation kicks off.
What I Need
The SwiftUI .onAppear() and .onDisappear() methods are poorly named. They should really be called .onInsertion() and .onRemoval(), because they are only called when the view is added/removed from the hierarchy. (The "on appear" and "on disappear" names have historical meaning from NSViewController and Apple should never have recycled those names for a different intent.) As such, I cannot use these methods to start/stop the animation. .onAppear() is ever called only once and .onDisappear() is never called at all.
This animation should run continuously whenever the view is ON-SCREEN and then stop when the view disappears. So I need a replacement for .onAppear() and .onDisappear() that.....actually do what they imply they do!
My current approach is very hacky. From the NSViewController that holds the NSHostingView, I do this:
extension PopoverController: NSPopoverDelegate
{
func popoverWillShow(_ notification: Notification)
{
hostingView.rootView.popoverDidAppear()
}
func popoverDidClose(_ notification: Notification)
{
hostingView.rootView.popoverDidDisappear()
}
}
Where popoverDidAppear() and popoverDidDisappear() are two functions I've added to the PopoverView that replace the animation completely, as appropriate. (You can get rid of a .repeatForever() animation by replacing it with a new animation that is finite.)
But...this CANNOT be the right way, can it? There MUST be a canonical SwiftUI solution here that I just don't know about? Surely the future of Apple UI frameworks cannot need AppKit's help just to know when a view is shown and not shown?
This approach works, but I don't know if it's the "correct" way:
1. Add a Published Property in AppKit
To the NSViewController that manages the NSHostingView, I added this:
final class PopoverController: NSViewController, NSPopoverDelegate
{
#Published var popoverIsVisible: Bool = false
func popoverWillShow(_ notification: Notification)
{
popoverIsVisible = true
}
func popoverDidClose(_ notification: Notification)
{
popoverIsVisible = false
}
}
2. Use Combine in SwiftUI
In my SwiftUI view, I then did this:
struct PopoverView: View
{
#ObservedObject var popoverController: PopoverController
#State private var buttonWidthScale: CGFloat = 1.0
var body: some View
{
Button {
...
} label: {
RoundedRectangle(cornerRadius: 6.0)
.fill(.blue)
.scaleEffect(CGSize(width: buttonWidthScale, height: 1))
.onReceive(popoverController.$popoverIsVisible.dropFirst()) { isVisible in
if isVisible
{
withAnimation(.easeInOut(duration: 2.5).repeatForever()) {
buttonWidthScale = 0.96
}
}
else
{
// Replacing the repeating animation with a non-repeating one eliminates all animations.
withAnimation(.linear(duration: 0.001)) {
buttonWidthScale = 1.0
}
}
}
}
}
}
This appears to resolve the issue: CPU usage drops back to 0% when the popover is closed and the SwiftUI view leaves screen. The animation works correctly whenever the view appears.
But, again, there must be a better way to do this, right? This is a bunch of tight coupling and extra work just to accomplish something that ought to be automatic: "Don't waste CPU cycles on animations if the views aren't even on screen." Surely I'm just missing a SwiftUI idiom or modifier that does that?
I am trying to hide the navigation bar in SwiftUI, able to hide the navigation bar but it disables user-interaction of my header button.
I use the below code to hide the navigation bar.
.navigationBarBackButtonHidden(true).navigationBarHidden(true).navigationBarTitle("")
The above code work in another view but not working in Dashboard.
When I move to another view and come back to the dashboard then the navigation bar hides properly.
I also try this
NavigationLink(destination: MainTabBarView().navigationBarBackButtonHidden(true).navigationBarHidden(true).navigationBarTitle(""), isActive: $isPushHome) but no luck.
You have also another options in the toolbar.
Please try the following code :
var body: some View {
NavigationView {
VStack{
Text("Content").font(.largeTitle)
Spacer()
}
.padding()
.navigationBarTitleDisplayMode(.inline)
.toolbar(content: {
ToolbarItem(placement: .navigationBarTrailing){
Button(action: {}, label: {
Text("Test")
})
}
})
.navigationBarBackButtonHidden(true)
}
}
I'm trying to show a WKWebView in SwiftUI on MacOS. When the app initially loads, the WKWebView has a large, white bar at the top. Moving or resizing the window causes this to immediately disappear and display correctly. Interestingly, the blue border around the view does not exhibit the bad behavior.
My guess is that I'm missing some action in updateNSView.
I'm on MacOS 11.1 Big Sur, Xcode 12.2, Intel. Another thing to note is that I need to enable the "Outgoing Connections" entitlement in the App Sandbox to get WKWebView to render anything at all, even tho the content is provided locally from a string.
import SwiftUI
import WebKit
#main
struct ProblemWKWebViewApp: App {
var body: some Scene {
WindowGroup {
SwiftUIWebView()
.border(Color.blue, width: 2)
}
}
}
struct SwiftUIWebView: NSViewRepresentable {
public typealias NSViewType = WKWebView
func makeNSView(context: Context) -> WKWebView {
let webView = WKWebView()
webView.loadHTMLString("<body style=\"background-color: red;\"><h1>Hello World!</h1></body>", baseURL: nil)
return webView
}
func updateNSView(_ nsView: WKWebView, context: Context) {
}
}
I had the same problem. I suppose that it is a bug. However I managed to fix it with adding ignoresSafeArea():
#main
struct ProblemWKWebViewApp: App {
var body: some Scene {
WindowGroup {
SwiftUIWebView()
.border(Color.blue, width: 2)
// Shows weird black bar on top without this on macOS
.ignoresSafeArea()
}
}
}
I want to make a parallax background view, where the image behind the UI stays nearly still as the window moves around on the screen. To do this on macOS, I want to get the window's coordinates. How do I get the window's coordinates?
I ask this because I can't find anywhere that says how to do this:
Google searches which helped me find the following results:
SwiftUI window coordinates, SwiftUI window location, SwiftUI window get frame, SwiftUI get window, SwiftUI macOS window coordinates, SwiftUI macOS window location, SwiftUI macOS window get frame, SwiftUI macOS get window
Apple Developer Documentation:
GeometryReader - I had hoped that this would contain an API to give me the frame in system coordinate space, but it seems all the approaches it contains only reference within-the-window coordinates
Creating a macOS App — SwiftUI Tutorials - I was hoping Apple would have mentioned windowing in this, but it's not mentioned at all, aside from saying that you can preview the main window's contents in an Xcode preview pane
Fruitless searches: SwiftUI window coordinates, SwiftUI window location, SwiftUI window get frame
Other SO questions:
How to access own window within SwiftUI view? - I was optimistic that this would have an answer which would give me a SwiftUI API to access the window, but instead it uses a shim to access the AppKit window representation.
Define macOS window size using SwiftUI - Similar hopes as the above question, but this time the answer was just to read the frame of the content view, which again, always has a (0, 0) origin
SwiftUI coordinate space - I was hoping this answer would let me know how to transform the coordinates given by GeometryReader into screen coordinates, but unfortunately the coordinates are again constrained to within the window
Elsewhere on the web:
SwiftUI for Mac - Part 2 by TrozWare - I was hoping that this would give me some tips for using SwiftUI on Mac, such as interacting with windows, since most tutorials focus on iOS/iPadOS. Unfortunately, although it has lots of good information about how SwiftUI works with windows, it has no information on interacting with nor parsing those windows, themselves
SwiftUI Layout System by Alexander Grebenyuk - Was hoping for window layout within the screen, but this is all for full-screen iOS apps
SwiftUI by Example by Hacking with Swift - Was hoping for an example for how to get the position of a window, but it seems windows aren't really mentioned at all in the listed examples
As I listed, I found that all these either didn't relate to my issue, or only reference the coordinates within the window, but not the window's coordinates within the screen. Some mention ways to dip into AppKit, but I want to avoid that if possible.
The closest I got was trying to use a GeometryReader like this:
GeometryReader { geometry in
Text(verbatim: "\(geometry.frame(in: .global))")
}
but the origin was always (0, 0), though the size did change as I adjusted the window.
What I was envisioning was something perhaps like this:
public struct ParallaxBackground<Background: View>: View {
var background: Background
#Environment(\.windowFrame)
var windowFrame: CGRect
public var body: some View {
background
.offset(x: windowFrame.minX / 10,
y: windowFrame.minY / 10)
}
}
but \.windowFrame isn't real; it doesn't point to any keypath on EnvironmentValues. I can't find where I would get such a value.
As of today we have macOS 12 widely deployed/installed and SwiftUI has not gained a proper model for the macOS window. And from what I learned so far about macOS 13, there won't be a SwiftUI model for the window coming either.
Today (since macOS 11) we are not opening windows in the AppDelegate anymore but are now defining windows using the WindowGroup scene modifiers:
#main
struct HandleWindowApp: App {
var body: some Scene {
WindowGroup(id: "main") {
ContentView()
}
}
}
But there is no standard way to control or access the underlying window (e.g. NSWindow). To do this multiple answers on stackoverflow suggest to use a WindowAccessor which installs a NSView in the background of the ContentView and then accessing its window property. I also wrote my version of it to control the placement of windows.
In your case, it is sufficient to get a handle to the NSWindow instance and then observe the NSWindow.didMoveNotification. It will get called whenever the window did move.
If your app is using only a single window (e.g. you somehow inhibit that multiple windows can be created by the user), you can even observe the frames positions globally:
NotificationCenter.default
.addObserver(forName: NSWindow.didMoveNotification, object: nil, queue: nil) { (notification) in
if let window = notification.object as? NSWindow,
type(of: window).description() == "SwiftUI.SwiftUIWindow"
{
print(window.frame)
}
}
If you want the window frame:
The SceneDelegate keeps track of all the windows, so you can use it to make an EnvironmentObject with a reference to their frames and pass that to your View. Update the environment object values in the delegate method: func windowScene(_ windowScene: UIWindowScene, didUpdate previousCoordinateSpace: UICoordinateSpace, ...
If it's a one window app, it's much more straight forward. You could use UIScreen.main.bounds (if full screen) or a computed variable in you view:
var frame: CGRect { (UIApplication.shared.connectedScenes.first?.delegate as? SceneDelegate)?.window?.frame ?? .zero }
But if you are looking for the frame of the view in the window, try something like this:
struct ContentView: View {
#State var frame: CGRect = .zero
var orientationChangedPublisher = NotificationCenter.default.publisher(for: UIDevice.orientationDidChangeNotification)
var body: some View {
VStack {
Text("text frame georeader \(frame.debugDescription)")
}
.background(GeometryReader { geometry in
Color.clear // .edgesIgnoringSafeArea(.all) // may need depending
.onReceive(self.orientationChangedPublisher.removeDuplicates()) { _ in
self.frame = geometry.frame(in: .global)
}
})
}
}
But having said all that, usually you don't need an absolute frame. Alignment guides let you place things relative to each other.
// For macOS App, using Frame Changed Notification and passing as Environment Object to SwiftUI View
class WindowInfo: ObservableObject {
#Published var frame: CGRect = .zero
}
#NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {
var window: NSWindow!
let windowInfo = WindowInfo()
func applicationDidFinishLaunching(_ aNotification: Notification) {
// Create the SwiftUI view that provides the window contents.
let contentView = ContentView()
.environmentObject(windowInfo)
// Create the window and set the content view.
window = NSWindow(
contentRect: NSRect(x: 0, y: 0, width: 480, height: 300),
styleMask: [.titled, .closable, .miniaturizable, .resizable, .fullSizeContentView],
backing: .buffered, defer: false)
window.center()
window.setFrameAutosaveName("Main Window")
window.contentView = NSHostingView(rootView: contentView)
window.contentView?.postsFrameChangedNotifications = true
window.makeKeyAndOrderFront(nil)
NotificationCenter.default.addObserver(forName: NSView.frameDidChangeNotification, object: nil, queue: nil) { (notification) in
self.windowInfo.frame = self.window.frame
}
}
struct ContentView: View {
#EnvironmentObject var windowInfo: WindowInfo
var body: some View {
Group {
Text("Hello, World! \(windowInfo.frame.debugDescription)")
.frame(maxWidth: .infinity, maxHeight: .infinity)
}
}
}
Is there a way to show dark mode and light mode side by side in Xcode 11?
I'm using UIKit / UIViewControllers.
(
Using SwiftUI and previews this can be done but does not apply to UIKit:
#if DEBUG
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
Group {
ContentView()
.environment(\.colorScheme, .light)
ContentView()
.environment(\.colorScheme, .dark)
}
}
}
#endif
)
When you use Storyboards, you can change the Interface Style of the preview.
When running, you can use the Environment Overrides to toggle between light and dark mode. But both option won't show the view side-by-side.
What you can probably do is to wrap your UIKit view in a helper SwiftUI View using UIViewRepresentable and display that in the preview canvas. That should work for embedded UIKit content.