Write non-URL data to tag

[JeffreyParticipant]

I am curious if there is a way to write an arbitrary string as an NDEF message using the iOS SDK/Objective C. I see that FmNdefMessage has a createURIWithString method, but it has no other public method to create a message from anything else.
Thanks!

[ScottKeymaster]

Hi Jeffrey,

Yes this is possible. You would need to create a FmNdefRecord with the specific details you’re looking for.

You can use Mime type records or Well Known Type records to store plain text.
Here is an example of a mime type record.

TNF – kTNFMimeMedia
Type – 74 65 78 74 2f 70 6c 61 69 6e (“text/plain” in hex)
id – nil
payload – <insert your text as ASCII bytes here> (Use NSString’s dataUsingEncoding:NSASCIIStringEncoding to convert your string to bytes)

You would then use the initWithNdefRecords initializer in FmNdefMessage

Hope this helps,
Scott

• This reply was modified 6 years, 4 months ago by  Scott.

[JeffreyParticipant]

Hey Scott — thanks for the reply. I admit that my Objective C is far from fantastic, but in the version of FmNdefMessage that I have, the method you mention is marked as private (or whatever the Objective C equivilent is)

– (id)initWithNdefRecords:(NSArray *)ndefRecords;

Same with the FmNdefRecord. All of the properties you mention are “readonly”, and the only public constructors are

+ (FmNdefRecord *)createURIWithURL:(NSURL *)url;
+ (FmNdefRecord *)createURIWithString:(NSString *)uriString;

None of the functions you mention appear in the autocomplete, and I get an error when I try to compile them. I get the error:

No known class method for selector ‘initWithTnf:andType:andId:andPayload:’

Can you point me to a code example somewhere?

Thanks

[ScottKeymaster]

Hi Jeffrey,

What version of the SDK are you using?
You may have to update.
flomio-sdk-ios repo

Here is how I would do it:

NSData *type = [@"text/plain" dataUsingEncoding:NSASCIIStringEncoding];
NSData *payload = [@"Hello World!" dataUsingEncoding:NSASCIIStringEncoding];
  FmNdefRecord *record = [[FmNdefRecord alloc] initWithTnf:kTNFMimeMedia andType:type andId:nil andPayload: payload];
FmNdefMessage *message = [[FmNdefMessage alloc] initWithNdefRecords:@[record]];
[tag writeNdef:message success:^(BOOL success) {
    if (success){
      NSLog(@"Tag Writing Successful");
    }
}];

Hope that helps,
Scott

• This reply was modified 6 years, 4 months ago by  Scott.
• This reply was modified 6 years, 4 months ago by  Scott.
• This reply was modified 6 years, 4 months ago by  Scott.

[JeffreyParticipant]

I thought I had the master version of the SDK from Github, but I updated it and the code seems to work, so thanks!

[ScottKeymaster]

Glad that got it sorted for you.

If you’re happy with the help and feel like giving us a review, you can do so here.
It makes a big difference to us

Kind Regards,
Scott

[Author]

Posts