RxSwift の Debug に寄せたロガー（メインスレッド判定もできる）

LoggerLikeRx.swift

enum Logger {
    static let dateFormatter: DateFormatter = {
        let df = DateFormatter()
        df.dateFormat = "yyyy-MM-dd HH:mm:ss.SSS"
        return df
    }()
    static func log(_ item: String, file: String = #file, line: UInt = #line, function: String = #function) {
        printLikeRxDebug(item, file, line, function)
    }
    static func isMainThread(file: String = #file, line: UInt = #line, function: String = #function) {
        printLikeRxDebug("Main Thread: \(Thread.isMainThread)", file, line, function)
    }
    private static func printLikeRxDebug(_ item: String, _ file: String, _ line: UInt, _ function: String) {
        let trimmedFile: String
        if let lastIndex = file.lastIndex(of: "/") {
            trimmedFile = String(file[file.index(after: lastIndex) ..< file.endIndex])
        } else {
            trimmedFile = file
        }
        print("\(Logger.dateFormatter.string(from: Date())): \(trimmedFile):\(line) (\(function)) -> \(item)")
    }
}