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

Disclaimer: Below is not really like a "native modal", neither behave nor look&feel, but if anyone would need a custom transition of one view over other, making active only top one, the following approach might be helpful.

So, if you expect something like the following

Here is a simple code for demo the approach (of corse animation & transition parameters can be changed by wish)

struct ModalView : View {
    @Binding var activeModal: Bool
    var body : some View {
        VStack {
            Button(action: {
                withAnimation(.easeInOut(duration: 0.3)) {
                    self.activeModal = false
                }
            }) {
                Text("Hide modal")
            }
            Text("Modal View")
        }
        .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: .infinity, alignment: .center)
        .background(Color.green)
    }
}

struct MainView : View {
    @Binding var activeModal: Bool
    var body : some View {
        VStack {
            Button(action: {
                withAnimation(.easeInOut(duration: 0.3)) {
                    self.activeModal = true
                }
            }) {
                Text("Show modal")
            }
            Text("Main View")
        }
        .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: .infinity, alignment: .center)
        .background(Color.yellow)
    }
}

struct ModalContainer: View {
    @State var showingModal = false
    var body: some View {
        ZStack {
            MainView(activeModal: $showingModal)
                .allowsHitTesting(!showingModal)
            if showingModal {
                ModalView(activeModal: $showingModal)
                    .transition(.move(edge: .bottom))
                    .zIndex(1)
            }
        }
    }
}

Answer 2

Here is a simple one way - forward views. It's very straight forward.

        struct ChildView: View{
           private  let colors: [Color] = [.red, .yellow,.green,.white]
           @Binding var index : Int
           var body: some View {
           let next = (self.index+1)  % MyContainer.totalChildren
             return   ZStack{
                    colors[self.index  % colors.count]
                     Button("myNextView \(next)   ", action: {
                    withAnimation{
                        self.index = next
                    }
                    }
                )}.transition(.asymmetric(insertion: .move(edge: .trailing)  , removal:  .move(edge: .leading)  ))
            }
        }

        struct MyContainer: View {
            static var totalChildren = 10
            @State private var value: Int = 0
            var body: some View {
                    HStack{
                        ForEach(0..<(Self.totalChildren) ) { index in
                            Group{
                            if    index == self.value {
                                ChildView(index:  self.$value)
                                }}
                            }
                }
                }
        }

Answer 3

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)
        )
        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
            }
        }
    }
}