Custom size popover in iOS SwiftUI

WithPopover.swift

// -- Usage

struct Content: View {
    @State var open = false
    @State var popoverSize = CGSize(width: 300, height: 300)
    
    var body: some View {
        WithPopover(
            showPopover: $open,
            popoverSize: popoverSize,
            content: {
                Button(action: { self.open.toggle() }) {
                    Text("Tap me")
                }
        },
            popoverContent: {
                VStack {
                    Button(action: { self.popoverSize = CGSize(width: 300, height: 600)}) {
                        Text("Increase size")
                    }
                    Button(action: { self.open = false}) {
                        Text("Close")
                    }
                }
        })
    }
}


// -- Source

struct WithPopover<Content: View, PopoverContent: View>: View {
    
    @Binding var showPopover: Bool
    var popoverSize: CGSize? = nil
    let content: () -> Content
    let popoverContent: () -> PopoverContent
    
    var body: some View {
        content()
        .background(
            Wrapper(showPopover: $showPopover, popoverSize: popoverSize, popoverContent: popoverContent)
                .frame(maxWidth: .infinity, maxHeight: .infinity)
        )
    }
    
    struct Wrapper<PopoverContent: View> : UIViewControllerRepresentable {
        
        @Binding var showPopover: Bool
        let popoverSize: CGSize?
        let popoverContent: () -> PopoverContent
        
        func makeUIViewController(context: UIViewControllerRepresentableContext<Wrapper<PopoverContent>>) -> WrapperViewController<PopoverContent> {
            return WrapperViewController(
                popoverSize: popoverSize,
                popoverContent: popoverContent) {
                    self.showPopover = false
            }
        }
        
        func updateUIViewController(_ uiViewController: WrapperViewController<PopoverContent>,
                                    context: UIViewControllerRepresentableContext<Wrapper<PopoverContent>>) {
            uiViewController.updateSize(popoverSize)

            if showPopover {
                uiViewController.showPopover()
            }
            else {
                uiViewController.hidePopover()
            }
        }
    }
    
    class WrapperViewController<PopoverContent: View>: UIViewController, UIPopoverPresentationControllerDelegate {
        
        var popoverSize: CGSize?
        let popoverContent: () -> PopoverContent
        let onDismiss: () -> Void
        
        var popoverVC: UIViewController?

        required init?(coder: NSCoder) { fatalError("") }
        init(popoverSize: CGSize?,
             popoverContent: @escaping () -> PopoverContent,
             onDismiss: @escaping() -> Void) {
            self.popoverSize = popoverSize
            self.popoverContent = popoverContent
            self.onDismiss = onDismiss
            super.init(nibName: nil, bundle: nil)
        }
        
        override func viewDidLoad() {
            super.viewDidLoad()
        }
        
        func showPopover() {
            guard popoverVC == nil else { return }
            let vc = UIHostingController(rootView: popoverContent())
            if let size = popoverSize { vc.preferredContentSize = size }
            vc.modalPresentationStyle = UIModalPresentationStyle.popover
            if let popover = vc.popoverPresentationController {
                popover.sourceView = view
                popover.delegate = self
            }
            popoverVC = vc
            self.present(vc, animated: true, completion: nil)
        }
        
        func hidePopover() {
            guard let vc = popoverVC, !vc.isBeingDismissed else { return }
            vc.dismiss(animated: true, completion: nil)
            popoverVC = nil
        }
        
        func presentationControllerWillDismiss(_ presentationController: UIPresentationController) {
            popoverVC = nil
            self.onDismiss()
        }
        
        func updateSize(_ size: CGSize?) {
            self.popoverSize = size
            if let vc = popoverVC, let size = size {
                vc.preferredContentSize = size
            }
        }
    }
}

if you add the following func you'll get the popover on iPhone as well

func adaptivePresentationStyle(for controller: UIPresentationController) -> UIModalPresentationStyle {
 return .none // this is what forces popovers on iPhone 
}

@wassupdoc Where should that func to be added ?

@ccwasden If the popovercontent is getting modiifed while using it, it doesn't reflect in the view

Ignore my above comment. I figured that out :)

Brilliant mate -- a real help to SwiftUI folks :-)

@dmallass - I'm having the same issue where the view isn't reflecting the underlying state changes. happen to remember what was causing that issue for you?

Yes, this didn't work on iPhone simulators on 15.2, but adding the function above (by @wassupdoc ) is what did it. Add it to the class, WrapperViewController.

@dmallass - I'm having the same issue where the view isn't reflecting the underlying state changes. happen to remember what was causing that issue for you?

I have solved this issue by adding the following code to func updateUIViewController after the if else pair:

if let hostingController = uiViewController.popoverVC as? UIHostingController<PopoverContent> {
    hostingController.rootView = popoverContent()
}

@sorin360 You should add that inside the UIPopoverPresentationControllerDelegate you want it to act on. In this case, WrapperViewController

I encountered a weird bug which sometime caused the popover to reopen itself as a sheet (iOS). While I don't know the cause for it i suspected may be it's due to something happening between the controllerWillDismiss and controllerDidDismiss. Therefore i moved the content in presentationControllerWillDismiss to presentationControllerDidDismiss. It fixed the issue

When I use this within a SwiftUI List, opening the popover will display a warning, that “presenting view controller [UIHostingController] from detached view controller [WrapperViewController] is discouraged” (when used outside of List, it's fine). I have spent some time trying to figure out what might be causing this, but I can't find a reason why WrapperViewController would be detached. Does anyone know what might be causing this?

With iOS 16.4 - haven’t had a chance to test it myself but the new presentationCompactAdaptation(.none) modifier may work - Apples documentation - Apply the new .presentationCompactAdaptation(_:) modifier to the content of a modal presentation to control how it adapts to compact size classes on iPad and iPhone.
For example, the popover modifier presents a popover on iPad. By default, a popover adapts to the narrow horizontal size class on iPhone by showing as a sheet. In the example below, the .presentationCompactAdaptation(.none) modifier asks SwiftUI to show this as a popover on iPhone as well.
struct PopoverExample: View {
@State private var isShowingPopover = false

  var body: some View {
      Button("Show Popover") {
          self.isShowingPopover = true
      }
      .popover(isPresented: $isShowingPopover) {
          Text("Popover Content")
              .padding()
              .presentationCompactAdaptation(.none)
      }
  }

}
Use .presentationCompactAdaptation(horizontal:vertical:) to adapt differently in horizontally and vertically compact size classes. (103257577)

@INuvanda: Yes, there is this warning all the time and its getting worse with Xcode 15 beta: Here it's stated that this will be an error in future releases. I used these two nice extensions

extension UIWindow {
    static var key: UIWindow? {                                     // replacement of keyWindow
        if #available(iOS 13, *) {
                // from: https://stackoverflow.com/questions/57134259/how-to-resolve-keywindow-was-deprecated-in-ios-13-0
            return UIApplication
                .shared
                .connectedScenes
                .compactMap { $0 as? UIWindowScene }
                .flatMap { $0.windows }
                .last { $0.isKeyWindow }
        } else {
            return UIApplication.shared.keyWindow
        }
    }
}

extension UIViewController {
        // from https://stackoverflow.com/questions/26667009/get-top-most-uiviewcontroller
    static var topMostViewController: UIViewController? {
        var topMostViewController = UIWindow.key?.rootViewController    // the starting vc
        while let presentedViewController = topMostViewController?.presentedViewController {
            topMostViewController = presentedViewController         // loop over all presented vcs
        }
        return topMostViewController                                // and return the last/topmost one
    }
}

to modify the function showPopover():

        func showPopover() {
            guard popoverVC == nil,
            let topMostViewController = Self.topMostViewController else { return }
            let vc = UIHostingController(rootView: popoverContent())
            if let size = popoverSize { vc.preferredContentSize = size }
            vc.modalPresentationStyle = UIModalPresentationStyle.popover
            if let popover = vc.popoverPresentationController {
                popover.sourceView = view
                 popover.delegate = self
            }
            popoverVC = vc
            topMostViewController.present(vc, animated: true, completion: nil)    // present from topmost VC
        }

and the warning is gone.