Building Echo customizable log format #2. Full post: http://clmntcrl.io/blog/building-echo-customizable-log-format/.

EchoComponent.swift

enum EchoComponent {
    case DateTime
    case Flag
    case Filename
    case Function
    case Line
    case Message
}
extension EchoComponent: Printable {
    public var description: String {
        switch self {
        case .DateTime:
            return "[datetime]"
        case .Flag:
            return "[flag]"
        case .Filename:
            return "[filename]"
        case .Function:
            return "[function]"
        case .Line:
            return "[line]"
        case .Message:
            return "[message]"
        }
    }
}

EchoFormat.swift

struct Echo {
  var format = "\(EchoComponent.Flag) [\(EchoComponent.DateTime)] " + 
    "[\(EchoComponent.Filename):\(EchoComponent.Line)] \(EchoComponent.Message)"
}