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# TKSmartCardATR

A parsed ATR (Answer To Reset) message from a Smart Card.

```
class TKSmartCardATR
```

## Overview

This class declares a programmatic interface to parsing an ATR from data or a byte stream, and accessing the individual parts.

> Note:
> The ``doc://com.apple.cryptotokenkit/documentation/CryptoTokenKit/TKSmartCardATR`` class parses ATR messages according to the ISO/IEC 7816-3 specification.

## Topics

### Creating a Smart Card ATR

[`init(bytes:)`](/documentation/CryptoTokenKit/TKSmartCardATR/init(bytes:))

Initializes a `TKSmartCardATR` object from a provided data object.

[`init(source:)`](/documentation/CryptoTokenKit/TKSmartCardATR/init(source:))

Initializes a `TKSmartCardATR` object from a provided data source.

### Accessing ATR Attributes

[`protocols`](/documentation/CryptoTokenKit/TKSmartCardATR/protocols)

An array of protocols indicated in the ATR

[`bytes`](/documentation/CryptoTokenKit/TKSmartCardATR/bytes)

The ATR message data.

[`historicalBytes`](/documentation/CryptoTokenKit/TKSmartCardATR/historicalBytes)

The ATR historical bytes, not including interface bytes or the TCK (check byte).

[`historicalRecords`](/documentation/CryptoTokenKit/TKSmartCardATR/historicalRecords)

A list of compact TLV records parsed from historical bytes.

### Retrieving Interface Groups

[`interfaceGroup(at:)`](/documentation/CryptoTokenKit/TKSmartCardATR/interfaceGroup(at:))

Returns the interface group at the specified index.

[`interfaceGroup(for:)`](/documentation/CryptoTokenKit/TKSmartCardATR/interfaceGroup(for:))

Returns the interface group with the specified protocol.

[`TKSmartCardATR.InterfaceGroup`](/documentation/CryptoTokenKit/TKSmartCardATR/InterfaceGroup)

A single interface-bytes group for a Smart Card ATR (Answer to Reset).


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