Function handling debug messages to file

myMessageOutput.cpp

void myMessageOutput(QtMsgType type, const QMessageLogContext &context, const QString &msg) {
      Q_UNUSED(context)
      Q_UNUSED(type)
      QFile outFile(qgetenv("EXTERNAL_STORAGE") + QStringLiteral("/myApp-log.txt"));
      // EXTERNAL_STORAGE determines writable inner storage of device, for memory card use SECONDARY_STORAGE, but it may not exists
      if (outFile.open(QIODevice::WriteOnly | QIODevice::Append)) { // append line by line
        QTextStream ts(&outFile);
        ts << msg << endl;
    }
  }