Common type for aggregation all UI strings, that should be localized

Localized.swift

import Foundation

typealias Localized = String

extension Localized {
    
    func localize() -> String {
        return NSLocalizedString(self, comment: "")
    }
    
    /// Localize plural string key
    func localize<T>(_ count: T) -> String {
        return String.localizedStringWithFormat(self.localize(), count as! CVarArg)
    }
}

Example:

// Localized+Alert.swift
extension Localized {

    struct Alert {

        static var error: String = {
            return "general.alert.error".localize()
        }()
        // ...
    }
}

//...

let _ = Localized.Alert.error