Скачать или смотреть Troubleshooting: Cannot Read Specific NDEF Record with iPhone (iOS)

Discover why your iPhone cannot read specific NDEF records on ISO 15693 NFC tags and learn how to solve the issue effectively.
---
This video is based on the question https://stackoverflow.com/q/76466944/ asked by the user 'Andy Victors' ( https://stackoverflow.com/u/12648846/ ) and on the answer https://stackoverflow.com/a/76467604/ provided by the user 'Andy Victors' ( https://stackoverflow.com/u/12648846/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Cannot read specific NDEF record with iPhone (iOS)

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Troubleshooting: Cannot Read Specific NDEF Record with iPhone (iOS)

Have you ever encountered a frustrating situation where your NFC tag isn’t readable by your iPhone, yet it works seamlessly with Android devices? You’re not alone! This is a common problem that many users have faced when dealing with NFC tags, particularly those formatted with NDEF records. Below, we’ll dive into the issue and outline the steps to resolve it, ensuring that your NFC tags can be read on both platforms without a hitch.

The Problem

You’ve created a custom NFC tag with three NDEF records, including a URL and a couple of custom records. Initially, everything is in good working order. However, after increasing the size of the URL NDEF record, you discover that the iPhone no longer recognizes the tag, returning an empty NDEF record list. While Android devices handle the tag without any issues, the inconsistency raises questions.

Key Observations

The NDEF records worked perfectly before increasing the URL size.

Padding the URL makes the tag readable, but this is not a viable solution due to strict content size limitations.

The problem persists across various iPhone models running iOS 15 and iOS 16.

Manual validation confirms that all fields in the NDEF record are accurate and consistent.

Uncovering the Cause: ISO 15693 Tags

After some troubleshooting, we identified that the problem lies with the ISO 15693 tags. These tags include a critical component called the Capability Container, a 4-byte field located at user address 0x0. This header provides essential data about the tag, specifically the “size of content” formatted in 8-byte chunks. The size must be accurately represented to ensure compatibility.

What Went Wrong?

In our case, the size of content was represented as 0x12, which translates to 0x24 blocks. This means my content size was appropriately aligned with the tag specifications, which would suggest there is no violation. However, despite this correct configuration, the NDEF message was not recognized by the iPhone.

Finding a Solution

The breakthrough came when we incremented the content size by just 1 unit (an additional 8 bytes). Miraculously, the tag became readable again!

Steps to Resolve the Issue

Check Capability Container: Ensure that the size of your content is accurately reflected in the Capability Container of the ISO 15693 tag.

Adjust Content Size: If your NDEF records are on the edge of being unrecognized, try increasing your content size slightly. Even a small increment can make a difference.

Re-validate NDEF Records: Use available NDEF checking tools to confirm that all fields are correctly formatted and validated before retrying.

Conclusion

If you find yourself struggling with NDEF records that seem unreadable on iPhones, especially when working with ISO 15693 tags, remember that even minor adjustments in data size can resolve the issue. Taking the time to understand how the Capability Container works will also help ensure you’re developing NFC tags that work across platforms seamlessly.

Do you have more questions about NFC tags or need further assistance? Feel free to leave a comment below, and we’ll be happy to help!