Basic UIResponder for iOS error propagation

UIResponder+BasicErrorPropagation.swift

import UIKit

// The status of an error handler
enum ErrorHandlingStatus {
    /// The error was handled successfully and the propagation should stop
    case handled
    /// The error was not handled and the should be propagated further more
    case unhandled
}

/// Conforming to this protocol allows for error handling
protocol ErrorHandler {
    /// Handle an error
    ///
    /// - Parameter error: The error raised
    /// - Returns: The handled status
    func handleError(_ error: Error) -> ErrorHandlingStatus
}

// MARK: - Error Propagation
extension UIResponder {
    /// Raise an error and propagate it through the error chain
    ///
    /// - Parameter error: The error to be raised
    func raiseError(error: Error) {
        // Check if the next responder can handle errors
        guard let errorHandler = next as? ErrorHandler else {
            // If not then carry on the raise of the error
            next?.raiseUserError(error)
            return
        }
        
        // If the next responder is an error handler, then ask it to handle the error and check the result
        switch errorHandler.handleError(error) {
        case .unhandled:
            // If the error could not be handled, continue the propagation
            next?.raiseUserError(error)
        case .handled:
            // If the error was handled, stop the propagation
            break
        }
    }
}