A patch for SwiftUI views that disables keyboard avoidance

View+KeyboardAvoidance.swift

import InterposeKit
import UIKit
import SwiftUI
import SwiftUIIntrospect

extension View {
    public func keyboardAvoidanceDisabled() -> some View {
        self.introspect(.viewController, on: .iOS(.v17)) { viewController in
            if let hostingView = viewController.parent?.view {
                if String(describing: type(of: hostingView)).hasPrefix("_UIHostingView") {
                    hostingView.installPatchForDisablingKeyboardAvoidanceIfNeeded()
                }
            }
        }
    }
}

// https://steipete.com/posts/disabling-keyboard-avoidance-in-swiftui-uihostingcontroller/
extension UIView {
    fileprivate func installPatchForDisablingKeyboardAvoidanceIfNeeded() {
        guard !self.isKeyboardAvoidanceDisablingPatchInstalled else { return }
        defer { self.isKeyboardAvoidanceDisablingPatchInstalled = true }
        
        do {
            try self.hook(
                Selector(("keyboardWillShowWithNotification:")),
                methodSignature: (@convention(c) (UIView, Selector, Notification) -> Void).self,
                hookSignature: (@convention(block) (UIView, Notification) -> Void).self
            ) { hook in
                return { _, _ in /* noop */ }
            }
            
            try self.hook(
                Selector(("keyboardWillHideWithNotification:")),
                methodSignature: (@convention(c) (UIView, Selector, Notification) -> Void).self,
                hookSignature: (@convention(block) (UIView, Notification) -> Void).self
            ) { hook in
                return { _, _ in /* noop */ }
            }
        } catch {
            assertionFailure(
                """
                \(UIView.self): Failed applying patch for disabling keyboard avoidance.
                """
            )
        }
    }
}

extension UIView {
    fileprivate var isKeyboardAvoidanceDisablingPatchInstalled: Bool {
        get { self.getAssociatedObject(forKey: .isKeyboardAvoidanceDisablingPatchInstalled, default: false) }
        set { self.setAssociatedObject(newValue, forKey: .isKeyboardAvoidanceDisablingPatchInstalled) }
    }
}

extension AssociationKeys {
    fileprivate static let isKeyboardAvoidanceDisablingPatchInstalled = AssociationKey<Bool>()
}