SwiftUI - PresentationButton with modal that is full screen

Question

I am trying to implement a button that presents another scene with a "Slide from Botton" animation.

PresentationButton looked like a good candidate, so I gave it a try:

import SwiftUI

struct ContentView : View {
    var body: some View {
        NavigationView {
            PresentationButton(destination: Green().frame(width: 1000.0)) {
                Text("Click")

                }.navigationBarTitle(Text("Navigation"))
        }
    }
}

#if DEBUG
struct ContentView_Previews : PreviewProvider {
    static var previews: some View {
        Group {
            ContentView()
                .previewDevice("iPhone X")
                .colorScheme(.dark)

            ContentView()
                .colorScheme(.dark)
                .previewDevice("iPad Pro (12.9-inch) (3rd generation)"

            )

        }

    }
}
#endif

And here is the result:

I want the green view to cover the whole screen, and also the modal to be not "draggable to close".

Is it possible to add modifier to PresentationButton to make it full screen, and not draggable?

I have also tried a Navigation Button, but: - It doesn't "slide from bottom" - It creates a "back button" on detail view, which I don't want

thanks!

Answer 1

Although my other answer is currently correct, people probably want to be able to do this now. We can use the Environment to pass a view controller to children. Gist here

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: UIViewControllerHolder {
        get { return self[ViewControllerKey.self] }
        set { self[ViewControllerKey.self] = newValue }
    }
}

Add an extension to UIViewController

extension UIViewController {
    func present<Content: View>(style: UIModalPresentationStyle = .automatic, @ViewBuilder builder: () -> Content) {
        // Must instantiate HostingController with some sort of view...
        let toPresent = UIHostingController(rootView: AnyView(EmptyView()))
        toPresent.modalPresentationStyle = style
        // ... but then we can reset rootView to include the environment
        toPresent.rootView = AnyView(
            builder()
                .environment(\.viewController, ViewControllerHolder(value: toPresent))
        )
        self.present(toPresent, animated: true, completion: nil)
    }
}

And whenever we need it, use it:

struct MyView: View {

    @Environment(\.viewController) private var viewControllerHolder: ViewControllerHolder
    private var viewController: UIViewController? {
        self.viewControllerHolder.value
    }

    var body: some View {
        Button(action: {
           self.viewController?.present(style: .fullScreen) {
              MyView()
           }
        }) {
           Text("Present me!")
        }
    }
}

[EDIT] Although it would be preferable to do something like @Environment(\.viewController) var viewController: UIViewController? this leads to a retain cycle. Therefore, you need to use the holder.

Answer 2

Xcode 12.0 - SwiftUI 2 - iOS 14

Now possible. Use fullScreenCover() modifier.

var body: some View {
    Button("Present!") {
        self.isPresented.toggle()
    }
    .fullScreenCover(isPresented: $isPresented, content: FullScreenModalView.init)
}

Hacking With Swift