Fix SwiftUI Menu Backdrop Penetration.

SwiftUIMenuBackdropPenetrationFix.swift

import UIKit

// https://devnotes.by.sb/apple/swiftui/menu-backdrop-not-blocking-user-interactions
class SwiftUIMenuBackdropPenetrationFix: UIView {
    // _UIContextMenuPlatterTransitionView
    static let transitionViewClass: AnyClass? = NSClassFromString("_UIContextMenuPlatterTransitionView")
    // _UIContextMenuContainerView
    static let containerViewClass: AnyClass? = NSClassFromString("_UIContextMenuContainerView")

    static func swizzle() {
        let didAddSubviewSelector = #selector(didAddSubview(_:))
        let willRemoveSubviewSelector = #selector(willRemoveSubview(_:))
        let willMoveToWindowSelector = #selector(willMove(toWindow:))
        let originalDidAddSubviewMethod = class_getInstanceMethod(
            SwiftUIMenuBackdropPenetrationFix.containerViewClass,
            didAddSubviewSelector
        )
        let originalWillRemoveSubviewMethod = class_getInstanceMethod(
            SwiftUIMenuBackdropPenetrationFix.containerViewClass,
            willRemoveSubviewSelector
        )
        let originalWillMoveToWindowMethod = class_getInstanceMethod(
            SwiftUIMenuBackdropPenetrationFix.containerViewClass,
            willMoveToWindowSelector
        )
        let swizzledDidAddSubviewMethod = class_getInstanceMethod(
            SwiftUIMenuBackdropPenetrationFix.self,
            didAddSubviewSelector
        )
        let swizzledWillRemoveSubviewMethod = class_getInstanceMethod(
            SwiftUIMenuBackdropPenetrationFix.self,
            willRemoveSubviewSelector
        )
        let swizzledWillMoveToWindowMethod = class_getInstanceMethod(
            SwiftUIMenuBackdropPenetrationFix.self,
            willMoveToWindowSelector
        )

        guard
            let swizzledDidAddSubviewMethod,
            let swizzledWillRemoveSubviewMethod,
            let swizzledWillMoveToWindowMethod
        else {
            fatalError("SwiftUIMenuBackdropPenetrationFix: Swizzled methods don't exist.")
        }

        if let originalDidAddSubviewMethod {
            method_exchangeImplementations(originalDidAddSubviewMethod, swizzledDidAddSubviewMethod)
        } else {
            let imp = method_getImplementation(swizzledDidAddSubviewMethod)
            let types = method_getTypeEncoding(swizzledDidAddSubviewMethod)
            class_addMethod(
                SwiftUIMenuBackdropPenetrationFix.containerViewClass,
                didAddSubviewSelector,
                imp,
                types
            )
        }
        if let originalWillRemoveSubviewMethod {
            method_exchangeImplementations(originalWillRemoveSubviewMethod, swizzledWillRemoveSubviewMethod)
        } else {
            let imp = method_getImplementation(swizzledWillRemoveSubviewMethod)
            let types = method_getTypeEncoding(swizzledWillRemoveSubviewMethod)
            class_addMethod(
                SwiftUIMenuBackdropPenetrationFix.containerViewClass,
                willRemoveSubviewSelector,
                imp,
                types
            )
        }
        if let originalWillMoveToWindowMethod {
            method_exchangeImplementations(originalWillMoveToWindowMethod, swizzledWillMoveToWindowMethod)
        } else {
            let imp = method_getImplementation(swizzledWillMoveToWindowMethod)
            let types = method_getTypeEncoding(swizzledWillMoveToWindowMethod)
            class_addMethod(
                SwiftUIMenuBackdropPenetrationFix.containerViewClass,
                willMoveToWindowSelector,
                imp,
                types
            )
        }
    }

    @objc dynamic override func didAddSubview(_ subview: UIView) {
//        self.didAddSubview(subview)

        guard type(of: self) == SwiftUIMenuBackdropPenetrationFix.containerViewClass else { return }
        if type(of: subview) == SwiftUIMenuBackdropPenetrationFix.transitionViewClass {
            print("SwiftUIMenuBackdropPenetrationFix: \(self) Did add transitionViewClass")
            self.window?.rootViewController?.view.isUserInteractionEnabled = false
        }
    }

    @objc dynamic override func willRemoveSubview(_ subview: UIView) {
//        self.willRemoveSubview(subview)

        guard type(of: self) == SwiftUIMenuBackdropPenetrationFix.containerViewClass else { return }
        if type(of: subview) == SwiftUIMenuBackdropPenetrationFix.transitionViewClass {
            print("SwiftUIMenuBackdropPenetrationFix: \(self) Remove transitionViewClass")
            self.window?.rootViewController?.view.isUserInteractionEnabled = true
        }
    }

    @objc dynamic override func willMove(toWindow newWindow: UIWindow?) {
        guard type(of: self) == SwiftUIMenuBackdropPenetrationFix.containerViewClass else { return }
        if newWindow == nil {
            print("SwiftUIMenuBackdropPenetrationFix: \(self) Will be removed")
            self.window?.rootViewController?.view.isUserInteractionEnabled = true
        }
    }
}