[iOS] Can't Print A PDF With `printPdfFile`

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Introduction

Printing PDF files on iOS devices can be a complex task, especially when dealing with various printer models and settings. In this article, we will explore the issue of printing a PDF file using the printPdfFile method, which is not working as expected. We will also discuss the possible causes and solutions to this problem.

Symptoms

The issue is that the printPdfFile method is not printing the PDF file, despite the fact that the PDF is generated correctly and loaded in a preview before printing. The error code 6, which corresponds to ERROR_COMMUNICATION_ERROR, is returned when trying to print the PDF file.

Steps to Reproduce the Issue

To reproduce the issue, follow these steps:

  1. Connect the device to the printer: Make sure the device (RJ-4250WB) is connected in Settings->Bluetooth.
  2. Select the printer in the app: In the app, select the printer from the list.
  3. Press print: Press the print button to generate the PDF file.
  4. Generate the PDF file: The PDF file is generated in the temp directory (e.g. var/mobile/Containers/Data/Application/046DCC97-9A44-4A3D-A306-3D65373CD092/Library/Caches/generated.pdf).
  5. Call printer.printPdfFile(pdf, 1): Call the printPdfFile method with the generated PDF file and the desired print settings (in this case, 1).
  6. Print fails: The print operation fails with error code 6, which corresponds to ERROR_COMMUNICATION_ERROR.
  7. Check the printer connection: Look at Settings->Bluetooth and the printer has been disconnected.

Code Snippet

Here is the code snippet that demonstrates the issue:

var printerInfo = await settings.printerSettings.selectedPrinter?.getPrinterInfo()
var printerUtils = PrinterUtils()
var pdf = await printerUtils.getPdfPreviewPath(widget.ticket, printerInfo?.customPaperWidth ?? 153)

// Fails with the error code above
var result = await settings.printerSettings.selectedPrinter?.printPdfFile(pdf, 1)

// Works:
// var logoAsset = await loadImage('assets/images/print_test/account_logo.png')
// await settings.printerSettings.selectedPrinter?.printImage(logoAsset)

Possible Causes

Based on the symptoms and the code snippet, there are several possible causes for this issue:

  • Printer disconnection: The printer may be disconnecting from the device during the print operation, causing the printPdfFile method to fail.
  • Incorrect print settings: The print settings may be incorrect, causing the print operation to fail.
  • PDF file issues: The PDF file may be corrupted or not generated correctly, causing the print operation to fail.

Solutions

To solve this issue, try the following:

  • Check the printer connection: Make sure the printer is connected to the device and not disconnected during the print operation.
  • Verify the print settings: Check the print settings to ensure they are correct and not causing the print operation to fail.
  • Generate a new PDF file: Try generating a new PDF file to see if the issue is related to the PDF file itself.
  • Use a different print method: Try using a different print method, such as printImage, to see if the issue is specific to the printPdfFile method.

Conclusion

Printing PDF files on iOS devices can be a complex task, and issues like the one described in this article can be frustrating to resolve. By following the steps to reproduce the issue and checking the possible causes, you can try to solve the problem and get your PDF files printing correctly.

Additional Tips

  • Use a reliable printer: Make sure the printer is a reliable and well-supported model.
  • Check the device's Bluetooth settings: Ensure that the device's Bluetooth settings are correct and not causing the printer to disconnect.
  • Use a PDF viewer: Try using a PDF viewer to preview the PDF file before printing to ensure it is generated correctly.

Introduction

In our previous article, we explored the issue of printing a PDF file using the printPdfFile method on iOS devices. We discussed the symptoms, steps to reproduce the issue, and possible causes. In this article, we will provide a Q&A section to help you better understand the issue and find a solution.

Q: What is the error code 6, and what does it mean?

A: Error code 6 corresponds to ERROR_COMMUNICATION_ERROR. This error code indicates that there is a communication issue between the device and the printer, preventing the print operation from completing successfully.

Q: Why is the printer disconnecting during the print operation?

A: There are several possible reasons why the printer may be disconnecting during the print operation:

  • Bluetooth connection issues: The Bluetooth connection between the device and the printer may be weak or unstable, causing the printer to disconnect.
  • Printer settings: The printer settings may be incorrect, causing the printer to disconnect.
  • Device settings: The device settings may be incorrect, causing the printer to disconnect.

Q: How can I troubleshoot the issue?

A: To troubleshoot the issue, try the following:

  • Check the printer connection: Make sure the printer is connected to the device and not disconnected during the print operation.
  • Verify the print settings: Check the print settings to ensure they are correct and not causing the print operation to fail.
  • Generate a new PDF file: Try generating a new PDF file to see if the issue is related to the PDF file itself.
  • Use a different print method: Try using a different print method, such as printImage, to see if the issue is specific to the printPdfFile method.

Q: Can I use a different printer model?

A: Yes, you can try using a different printer model to see if the issue is specific to the current printer model. However, make sure the new printer model is compatible with your device and the print settings.

Q: How can I ensure the printer is connected to the device?

A: To ensure the printer is connected to the device, try the following:

  • Check the Bluetooth settings: Make sure the Bluetooth settings are correct and not causing the printer to disconnect.
  • Restart the device: Restart the device to ensure the Bluetooth connection is re-established.
  • Check the printer's Bluetooth settings: Make sure the printer's Bluetooth settings are correct and not causing the printer to disconnect.

Q: Can I use a PDF viewer to preview the PDF file before printing?

A: Yes, you can use a PDF viewer to preview the PDF file before printing to ensure it is generated correctly. This can help you identify any issues with the PDF file that may be causing the print operation to fail.

Q: How can I resolve the issue?

A: To resolve the issue, try the following:

  • Check the printer connection: Make sure the printer is connected to the device and not disconnected during the print operation.
  • Verify the print settings: Check the print settings to ensure they are correct and not causing the print operation to fail.
  • Generate a new PDF file: Try generating a new PDF file to see if the issue is related to the PDF file itself.
  • Use a different print method: Try using a different print method, such as printImage, to see if the issue is specific to the printPdfFile method.

By following these tips and troubleshooting the issue, you should be able to resolve the problem and get your PDF files printing correctly on your iOS device.