AWSLexPostContentRequest Class Reference

Inherits from AWSRequest : AWSModel : AWSMTLModel
Declared in AWSLexModel.h


You pass this value as the Accept HTTP header.

The message Amazon Lex returns in the response can be either text or speech based on the Accept HTTP header value in the request.

  • If the value is text/plain; charset=utf-8, Amazon Lex returns text in the response.

  • If the value begins with audio/, Amazon Lex returns speech in the response. Amazon Lex uses Amazon Polly to generate the speech (using the configuration you specified in the Accept header). For example, if you specify audio/mpeg as the value, Amazon Lex returns speech in the MPEG format.

    The following are the accepted values:

    • audio/mpeg

    • audio/ogg

    • audio/pcm

    • text/plain; charset=utf-8

    • audio/* (defaults to mpeg)

@property (nonatomic, strong) NSString *accept

Declared In



Alias of the Amazon Lex bot.

@property (nonatomic, strong) NSString *botAlias

Declared In



Name of the Amazon Lex bot.

@property (nonatomic, strong) NSString *botName

Declared In



You pass this values as the Content-Type HTTP header.

Indicates the audio format or text. The header value must start with one of the following prefixes:

  • PCM format

    • audio/l16; rate=16000; channels=1

    • audio/x-l16; sample-rate=16000; channel-count=1

  • Opus format

    • audio/x-cbr-opus-with-preamble; preamble-size=0; bit-rate=1; frame-size-milliseconds=1.1

  • Text format

    • text/plain; charset=utf-8

@property (nonatomic, strong) NSString *contentType

Declared In



User input in PCM or Opus audio format or text format as described in the Content-Type HTTP header.

@property (nonatomic, strong) NSInputStream *inputStream

Declared In



You pass this value in the x-amz-lex-session-attributes HTTP header. The value must be map (keys and values must be strings) that is JSON serialized and then base64 encoded.

A session represents dialog between a user and Amazon Lex. At runtime, a client application can pass contextual information, in the request to Amazon Lex. For example,

  • You might use session attributes to track the requestID of user requests.

  • In Getting Started Exercise 1, the example bot uses the price session attribute to maintain the price of flowers ordered (for example, "price":25). The code hook (Lambda function) sets this attribute based on the type of flowers ordered. For more information, see Review the Details of Information Flow.

  • In the BookTrip bot exercise, the bot uses the currentReservation session attribute to maintains the slot data during the in-progress conversation to book a hotel or book a car. For more information, see Details of Information Flow.

Amazon Lex passes these session attributes to the Lambda functions configured for the intent In the your Lambda function, you can use the session attributes for initialization and customization (prompts). Some examples are:

  • Initialization - In a pizza ordering bot, if you pass user location (for example, "Location : 111 Maple Street"), then your Lambda function might use this information to determine the closest pizzeria to place the order (and perhaps set the storeAddress slot value as well).

    Personalized prompts - For example, you can configure prompts to refer to the user by name (for example, "Hey [firstName], what toppings would you like?"). You can pass the user's name as a session attribute ("firstName": "Joe") so that Amazon Lex can substitute the placeholder to provide a personalized prompt to the user ("Hey Joe, what toppings would you like?").

Amazon Lex does not persist session attributes.

If you configured a code hook for the intent, Amazon Lex passes the incoming session attributes to the Lambda function. The Lambda function must return these session attributes if you want Amazon Lex to return them to the client.

If there is no code hook configured for the intent Amazon Lex simply returns the session attributes to the client application.

@property (nonatomic, strong) NSDictionary<NSString*NSString*> *sessionAttributes

Declared In



ID of the client application user. Typically, each of your application users should have a unique ID. The application developer decides the user IDs. At runtime, each request must include the user ID. Note the following considerations:

  • If you want a user to start conversation on one device and continue the conversation on another device, you might choose a user-specific identifier, such as the user's login, or Amazon Cognito user ID (assuming your application is using Amazon Cognito).

  • If you want the same user to be able to have two independent conversations on two different devices, you might choose device-specific identifier, such as device ID, or some globally unique identifier.

@property (nonatomic, strong) NSString *userId

Declared In