print listener

AppLogger

import Foundation
import CocoaLumberjack

typealias FilePath = String

final class AppLogger {

  private static let listener = ConsoleEavesdropper()

  // MARK: - Logger

  class var logFilesPaths: [FilePath] {
    get {
      let logers = DDLog.sharedInstance.allLoggers
      var logFiles: [FilePath] = []
      for logger in logers {
        if let currentLogger = logger as? DDFileLogger {
          let files = currentLogger.logFileManager.unsortedLogFileInfos.compactMap({ $0.filePath })
          logFiles.append(contentsOf: files)
        }
      }
      return logFiles
    }
  }

  class var content: String {
    var returnString: String = String.empty

    logFilesPaths.forEach({ (filePath) in
      if let data = try? Data(contentsOf: URL(fileURLWithPath: filePath)),
        let contentString = String(data: data, encoding: .utf8) {
        returnString += contentString
      }
    })

    return returnString
  }

  // MARK: - Configuration

  class func configure() {
    #if !PRODUCTIONMODE
      let fileLogger: DDFileLogger = DDFileLogger()
      fileLogger.rollingFrequency = TimeInterval(60 * 60 * 24)
      fileLogger.logFileManager.maximumNumberOfLogFiles = 1
      fileLogger.logFormatter = LogFormatter()
      DDLog.add(fileLogger, with: .all)

      DDLogVerbose(String.empty)
      DDLogVerbose(String.newLine)

      DDLogVerbose("starting app")
      let device = String(format: "Version: %@, Device: %@, %@, %@, UDID -> %@",
                          UIApplication.appVersion ?? "unknown",
                          UIDevice.current.modelName,
                          UIDevice.current.systemName,
                          UIDevice.current.systemVersion,
                          UIDevice.current.identifierForVendor?.uuidString ?? "nil")
      DDLogVerbose(device)

      listener.openConsolePipe()
      listener.onWishperDetection = { whishper -> Bool in
        DDLogVerbose(whishper)
        return true
      }
    #endif
  }

  class func clear() {
    logFilesPaths.forEach({ (filePath) in
      try? FileManager.default.removeItem(atPath: filePath)
    })
  }

  class func onAppTerminate() {
    #if !PRODUCTIONMODE
      DDLogVerbose("terminated app")
    #endif
  }

  class func onBackground() {
    #if !PRODUCTIONMODE
      DDLogVerbose("background app")
    #endif
  }

  class func onForeground() {
    #if !PRODUCTIONMODE
      DDLogVerbose("foreground app")
    #endif
  }
}

// MARK: - LogFormatter

fileprivate class LogFormatter: NSObject, DDLogFormatter { //swiftlint:disable:this private_over_fileprivate
  private let dateFormatter: DateFormatter

  override init() {
    dateFormatter = DateFormatter()
    dateFormatter.formatterBehavior = .behavior10_4
    dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss:SSS"

    super.init()
  }

  func format(message logMessage: DDLogMessage) -> String? {
    let dateAndTime = dateFormatter.string(from: logMessage.timestamp)
    return "\(dateAndTime) [\(logMessage.fileName):\(logMessage.line)]: \(logMessage.message)"
  }
}

ConsoleEavesdropper

import UIKit

final class ConsoleEavesdropper {

  private var inputPipe: Pipe?
  private var outputPipe: Pipe?

  var onWishperDetection: ((String) -> Bool)?

  func openConsolePipe() {
    inputPipe = Pipe()
    outputPipe = Pipe()

    guard let inputPipe = inputPipe,
      let outputPipe = outputPipe else {
        return
    }

    #if !os(iOS)
      return
    #endif

    let pipeReadHandle = inputPipe.fileHandleForReading

    dup2(STDOUT_FILENO, outputPipe.fileHandleForWriting.fileDescriptor)

    dup2(inputPipe.fileHandleForWriting.fileDescriptor, STDOUT_FILENO)
    dup2(inputPipe.fileHandleForWriting.fileDescriptor, STDERR_FILENO)

    NotificationCenter.default.addObserver(self, selector: #selector(self.handlePipeNotification), name: FileHandle.readCompletionNotification, object: pipeReadHandle)

    pipeReadHandle.readInBackgroundAndNotify()
  }

  @objc func handlePipeNotification(notification: Notification) {
    inputPipe?.fileHandleForReading.readInBackgroundAndNotify()

    if let data = notification.userInfo?[NSFileHandleNotificationDataItem] as? Data,
      let printWishper = String(data: data, encoding: String.Encoding.ascii) {

      if onWishperDetection?(printWishper) == false {
        return
      }
      outputPipe?.fileHandleForWriting.write(data)
    }
  }
}