Map this record to a URI, or return null if it cannot be mapped.

Currently this method considers the following to be URI records:

• NdefRecord.TnfAbsoluteUri records.
• NdefRecord.TnfWellKnown with a type of NdefRecord.RtdUri.
• NdefRecord.TnfWellKnown with a type of NdefRecord.RtdSmartPoster and containing a URI record in the NDEF message nested in the payload.
• NdefRecord.TnfExternalType records.

This method does not perform validation that the URI is actually valid: it always attempts to create and return a URI if this record appears to be a URI record by the above rules.

The returned URI will be normalized to have a lower case scheme using Android.Net.Uri.NormalizeScheme.

[Android Documentation]