Swiftui MACos Nswindow Instance

SwiftUI macos NSWindow instance

Although I am not entirely sure this is exactly the right approach, based on the answer to this question: https://stackoverflow.com/a/63439982/792406 I have been able to access the NSWindow instance and modify its appearance.

For quick reference, here's a working example based on the original code provided by Asperi using xcode 12.3, swift 5.3, and the SwiftUI App Life cycle.

@main
struct testApp: App {    
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}

class Store {
    var window: NSWindow
    
    init(window: NSWindow) {
        self.window = window
        self.window.isOpaque = false
        self.window.backgroundColor = NSColor.clear
    }
}

struct ContentView: View {
    @State private var window: NSWindow?
    var body: some View {
        VStack {
            Text("Loading...")
            if nil != window {
                MainView(store: Store(window: window!))
            }
        }.background(WindowAccessor(window: $window))
    }
}

struct MainView: View {

    let store: Store
    
    var body: some View {
        VStack {
            Text("MainView with Window: \(store.window)")
        }.frame(width: 400, height: 400)
    }
}

struct WindowAccessor: NSViewRepresentable {
    @Binding var window: NSWindow?
    
    func makeNSView(context: Context) -> NSView {
        let view = NSView()
        DispatchQueue.main.async {
            self.window = view.window
        }
        return view
    }
    
    func updateNSView(_ nsView: NSView, context: Context) {}
}

How to access NSWindow from @main App using only SwiftUI?

Basically, I'm trying to do something like:

LoginView(store: AuthStore(window: window))

Here is a demo of possible approach (with some replicated entities)

class AuthStore {
    var window: NSWindow

    init(window: NSWindow) {
        self.window = window
    }
}

struct DemoWindowAccessor: View {
    @State private var window: NSWindow?   // << detected in run-time so optional
    var body: some View {
        VStack {
            if nil != window {
                LoginView(store: AuthStore(window: window!))    // << usage
            }
        }.background(WindowAccessor(window: $window))
    }
}

struct WindowAccessor: NSViewRepresentable {
    @Binding var window: NSWindow?

    func makeNSView(context: Context) -> NSView {
        let view = NSView()
        DispatchQueue.main.async {
            self.window = view.window   // << right after inserted in window
        }
        return view
    }

    func updateNSView(_ nsView: NSView, context: Context) {}
}

struct LoginView: View {
    let store: AuthStore

    var body: some View {
        Text("LoginView with Window: \(store.window)")
    }
}

SwiftUI on MacOS. - Opening a new Window

Make your function generic and add view constraint.

static func newWindow<Content: View>(forSpecialView view: Content, title: String = "new Window") { // <-- Here

---

Another good and easy solution is to use View extension.

extension View {
    private func newWindowInternal(with title: String) -> NSWindow {
        let window = NSWindow(
            contentRect: NSRect(x: 20, y: 20, width: 680, height: 600),
            styleMask: [.titled, .closable, .miniaturizable, .resizable, .fullSizeContentView],
            backing: .buffered,
            defer: false)
        window.center()
        window.isReleasedWhenClosed = false
        window.title = title
        window.makeKeyAndOrderFront(nil)
        return window
    }
    
    func openNewWindow(with title: String = "new Window") {
        self.newWindowInternal(with: title).contentView = NSHostingView(rootView: self)
    }
}

Usage:

struct ContentView: View {
    var body: some View {
        Button(action: {
            ContentViewNewWindow().openNewWindow()
        }) {
            Text("Open New Window")
        }
    }
}

macOS SwiftUI, content does not fill NSWindow without titlebar

It looks I've reproduced what you might have

window.contentView = 
  NSHostingView(rootView: 
     Rectangle().fill(Color.red)
       .ignoresSafeArea()                 // << works !!
       .frame(width: 640, height: 480)
    // .ignoresSafeArea()             // << issue when here !!
  )

More findings: no issue even with ignoresSafeArea at the end when to use min W/H instead of strict frame for window, ie.

.frame(minWidth: 640, minHeight: 480)
.ignoresSafeArea()

---

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