enumCustomInit.swift

public enum FilterType: String, BaseSelectionType, CaseIterable {
    case colorDocument = "colorDocumentLocalization"
    case blackAndWhite = "blackAndWhiteLocalization"
    case colorPhoto = "colorPhotoLocalization"
    case greyscale = "greyscaleLocalization"
    case general = "generalLocalization" 
  
    func localizedString() -> String {
        return NSLocalizedString(self.rawValue, comment: "")
    }
  
    init(backendId: Int) {
        switch backendId {
        case 11: self = .colorDocument
        case 22: self = .blackAndWhite
        case 33: self = .colorPhoto
        case 44: self = .greyscale
        default: self = .general
        }
    }
}

// custom initialization example
let type = FilterType(id: 22)

print(type.localizedString())
//prints Black and White