ios - Present a new view in SwiftUI

Question

I want to click a button and then present a new view like present modally in UIKit

I have already seen "How to present a new view using sheets", but I don't want to attach it to the main view as a modal sheet.

And I don't want to use NavigationLink, because I don't want a new view and old view have a navigation relationship.

Thanks for your help...

Answer 1

To show a modal (iOS 13 style)

You just need a simple sheet with the ability to dismiss itself:

struct ModalView: View {
    @Binding var presentedAsModal: Bool
    var body: some View {
        Button("dismiss") { self.presentedAsModal = false }
    }
}

And present it like:

struct ContentView: View {
    @State var presentingModal = false
    
    var body: some View {
        Button("Present") { self.presentingModal = true }
        .sheet(isPresented: $presentingModal) { ModalView(presentedAsModal: self.$presentingModal) }
    }
}

_{Note that I passed the presentingModal to the modal so you can dismiss it from the modal itself, but you can get rid of it.}

---

To make it REALLY present fullscreen (Not just visually)

You need to access to the ViewController. So you need some helper containers and environment stuff:

struct ViewControllerHolder {
    weak var value: UIViewController?
}

struct ViewControllerKey: EnvironmentKey {
    static var defaultValue: ViewControllerHolder {
        return ViewControllerHolder(value: UIApplication.shared.windows.first?.rootViewController)

    }
}

extension EnvironmentValues {
    var viewController: UIViewController? {
        get { return self[ViewControllerKey.self].value }
        set { self[ViewControllerKey.self].value = newValue }
    }
}

Then you should use implement this extension:

extension UIViewController {
    func present<Content: View>(style: UIModalPresentationStyle = .automatic, @ViewBuilder builder: () -> Content) {
        let toPresent = UIHostingController(rootView: AnyView(EmptyView()))
        toPresent.modalPresentationStyle = style
        toPresent.rootView = AnyView(
            builder()
                .environment(.viewController, toPresent)
        )
        NotificationCenter.default.addObserver(forName: Notification.Name(rawValue: "dismissModal"), object: nil, queue: nil) { [weak toPresent] _ in
            toPresent?.dismiss(animated: true, completion: nil)
        }
        self.present(toPresent, animated: true, completion: nil)
    }
}

Finally

you can make it fullscreen like:

struct ContentView: View {
    @Environment(.viewController) private var viewControllerHolder: UIViewController?
    
    var body: some View {
        Button("Login") {
            self.viewControllerHolder?.present(style: .fullScreen) {
                Text("Main") // Or any other view you like
// uncomment and add the below button for dismissing the modal
            // Button("Cancel") {
            //       NotificationCenter.default.post(name: Notification.Name(rawValue: "dismissModal"), object: nil)
            //        }
            }
        }
    }
}