Getting current first responder

UIResponder+Current.swift

import UIKit

extension UIResponder {

    private static weak var _currentFirstResponder: UIResponder?

    public static var currentFirstResponder: UIResponder? {
        dispatchPrecondition(condition: .onQueue(.main))
        _currentFirstResponder = nil
        UIApplication.shared.sendAction(#selector(UIResponder.findFirstResponder(_:)), to: nil, from: nil, for: nil)
        return _currentFirstResponder
    }

    @objc private func findFirstResponder(_ sender: Any) {
        UIResponder._currentFirstResponder = self
    }
    
    public static var firstResponderExists: Bool {
        dispatchPrecondition(condition: .onQueue(.main))
        return currentFirstResponder != nil
    }
    
    public static func resignCurrentFirstResponder() {
        dispatchPrecondition(condition: .onQueue(.main))
        currentFirstResponder?.resignFirstResponder()
    }
}