bundesmessenger-ios/RiotSwiftUI/Modules/Common/SheetPresentation/SheetPresentation.swift

// 
// Copyright 2022 New Vector Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

import SwiftUI
import UIKit


// 1 - Create a UISheetPresentationController that can be used in a SwiftUI interface
@available(iOS 15.0, *)
struct SheetPresentationForSwiftUI<Content>: UIViewRepresentable where Content: View {
    
    @Binding var isPresented: Bool
    let onDismiss: (() -> Void)?
    let detents: [UISheetPresentationController.Detent]
    let content: Content
    
    init(
        _ isPresented: Binding<Bool>,
        onDismiss: (() -> Void)? = nil,
        detents: [UISheetPresentationController.Detent] = [.medium()],
        @ViewBuilder content: () -> Content
    ) {
        self._isPresented = isPresented
        self.onDismiss = onDismiss
        self.detents = detents
        self.content = content()
    }
    
    func makeUIView(context: Context) -> UIView {
        let view = UIView()
        return view
    }
    
    func updateUIView(_ uiView: UIView, context: Context) {
        
        // Create the UIViewController that will be presented by the UIButton
        let viewController = UIViewController()
        
        // Create the UIHostingController that will embed the SwiftUI View
        let hostingController = UIHostingController(rootView: content)
        
        // Add the UIHostingController to the UIViewController
        viewController.addChild(hostingController)
        viewController.view.addSubview(hostingController.view)
        
        // Set constraints
        hostingController.view.translatesAutoresizingMaskIntoConstraints = false
        hostingController.view.leftAnchor.constraint(equalTo: viewController.view.leftAnchor).isActive = true
        hostingController.view.topAnchor.constraint(equalTo: viewController.view.topAnchor).isActive = true
        hostingController.view.rightAnchor.constraint(equalTo: viewController.view.rightAnchor).isActive = true
        hostingController.view.bottomAnchor.constraint(equalTo: viewController.view.bottomAnchor).isActive = true
        hostingController.didMove(toParent: viewController)
        
        // Set the presentationController as a UISheetPresentationController
        if let sheetController = viewController.presentationController as? UISheetPresentationController {
            sheetController.detents = detents
            sheetController.prefersGrabberVisible = true
            sheetController.prefersScrollingExpandsWhenScrolledToEdge = false
        }
        
        // Set the coordinator (delegate)
        // We need the delegate to use the presentationControllerDidDismiss function
        viewController.presentationController?.delegate = context.coordinator
        
        
        if isPresented {
            // Present the viewController
            uiView.window?.rootViewController?.present(viewController, animated: true)
        } else {
            // Dismiss the viewController
            uiView.window?.rootViewController?.dismiss(animated: true, completion: onDismiss)
        }
        
    }
    
    /* Creates the custom instance that you use to communicate changes
    from your view controller to other parts of your SwiftUI interface.
     */
    func makeCoordinator() -> Coordinator {
        Coordinator(isPresented: $isPresented, onDismiss: onDismiss)
    }
    
    class Coordinator: NSObject, UISheetPresentationControllerDelegate {
        @Binding var isPresented: Bool
        let onDismiss: (() -> Void)?
        
        init(isPresented: Binding<Bool>, onDismiss: (() -> Void)? = nil) {
            self._isPresented = isPresented
            self.onDismiss = onDismiss
        }
        
        func presentationControllerDidDismiss(_ presentationController: UIPresentationController) {
            isPresented = false
            if let onDismiss = onDismiss {
                onDismiss()
            }
        }
        
    }
    
}

// 2 - Create the SwiftUI modifier conforming to the ViewModifier protocol
@available(iOS 15.0, *)
struct sheetWithDetentsViewModifier<SwiftUIContent>: ViewModifier where SwiftUIContent: View {
    
    @Binding var isPresented: Bool
    let onDismiss: (() -> Void)?
    let detents: [UISheetPresentationController.Detent]
    let swiftUIContent: SwiftUIContent
    
    init(isPresented: Binding<Bool>, detents: [UISheetPresentationController.Detent] = [.medium()] , onDismiss: (() -> Void)? = nil, content: () -> SwiftUIContent) {
        self._isPresented = isPresented
        self.onDismiss = onDismiss
        self.swiftUIContent = content()
        self.detents = detents
    }
    
    func body(content: Content) -> some View {
        ZStack {
            SheetPresentationForSwiftUI($isPresented,onDismiss: onDismiss, detents: detents) {
                swiftUIContent
            }.fixedSize()
            content
        }
    }
}

// 3 - Create extension on View that makes it easier to use the custom modifier
extension View {
    
    @available(iOS 15.0, *)
    func sheetWithDetents<Content>(
        isPresented: Binding<Bool>,
        detents: [UISheetPresentationController.Detent],
        onDismiss: (() -> Void)?,
        content: @escaping () -> Content) -> some View where Content : View {
            modifier(
                sheetWithDetentsViewModifier(
                    isPresented: isPresented,
                    detents: detents,
                    onDismiss: onDismiss,
                    content: content)
            )
        }
}