You can use ML Kit to generate message replies using an on-device model.
To generate smart replies, you pass ML Kit a log of recent messages in a conversation. If ML Kit determines the conversation is in English, and that the conversation doesn't have potentially sensitive subject matter, ML Kit generates up to three replies, which you can suggest to your user.
Before you begin
- If you have not already added Firebase to your app, do so by following the steps in the getting started guide .
- Include the ML Kit libraries in your Podfile:
pod 'Firebase/MLCommon', '6.25.0' pod 'Firebase/MLNLSmartReply', '6.25.0'
.xcworkspace. - In your app, import Firebase:
Swift
import Firebase
Objective-C
@import Firebase ;
1. Create a conversation history object
To generate smart replies, you pass ML Kit a chronologically-ordered array of TextMessage
objects, with the earliest timestamp first. Whenever the user
sends or receives a message, add the message, its timestamp, and the message
sender's user ID to the conversation history.
The user ID can be any string that uniquely identifies the sender within the conversation. The user ID doesn't need to correspond to any user data, and the user ID doesn't need to be consistent between conversations or invocations of the smart reply generator.
If the message was sent by the user you want to suggest replies to, set isLocalUser
to true.
Swift
var
conversation
:
[
TextMessage
]
=
[]
// Then, for each message sent and received:
let
message
=
TextMessage
(
text
:
"How are you?"
,
timestamp
:
Date
().
timeIntervalSince1970
,
userID
:
"userId"
,
isLocalUser
:
false
)
conversation
.
append
(
message
)
Objective-C
NSMutableArray
*
conversation
=
[
NSMutableArray
array
];
// Then, for each message sent and received:
FIRTextMessage
*
message
=
[[
FIRTextMessage
alloc
]
initWithText
:
@
"How are you?"
timestamp
:[
NSDate
date
].
timeIntervalSince1970
userID
:
userId
isLocalUser
:
NO
];
[
conversation
addObject
:
message
];
A conversation history object looks like the following example:
| Timestamp | User ID | Local User? | Message |
|---|---|---|---|
|
Thu Feb 21 13:13:39 PST 2019
|
true | are you on your way? | |
|
Thu Feb 21 13:15:03 PST 2019
|
FRIEND0 | false | Running late, sorry! |
Note that the most recent message in the example above is from a non-local user. This is important because ML Kit suggests replies intended to be sent by the user of your app: the local user. You should be sure you're passing ML Kit a conversation log that ends with a message to which your user might want to reply.
2. Get message replies
To generate smart replies to a message, get an instance of SmartReply
and pass
the conversation history to its suggestReplies(for:completion:)
method:
Swift
let
naturalLanguage
=
NaturalLanguage
.
naturalLanguage
()
naturalLanguage
.
smartReply
().
suggestReplies
(
for
:
conversation
)
{
result
,
error
in
guard
error
==
nil
,
let
result
=
result
else
{
return
}
if
(
result
.
status
==
.
notSupportedLanguage
)
{
// The conversation's language isn't supported, so the
// the result doesn't contain any suggestions.
}
else
if
(
result
.
status
==
.
success
)
{
// Successfully suggested smart replies.
// ...
}
}
Objective-C
FIRNaturalLanguage
*
naturalLanguage
=
[
FIRNaturalLanguage
naturalLanguage
];
FIRSmartReply
*
smartReply
=
[
naturalLanguage
smartReply
];
[
smartReply
suggestRepliesForMessages
:
inputText
completion
:
^
(
FIRSmartReplySuggestionResult
*
_Nullable
result
,
NSError
*
_Nullable
error
)
{
if
(
error
||
!
result
)
{
return
;
}
if
(
result
.
status
==
FIRSmartReplyResultStatusNotSupportedLanguage
)
{
// The conversation's language isn't supported, so the
// the result doesn't contain any suggestions.
}
else
if
(
result
.
status
==
FIRSmartReplyResultStatusSuccess
)
{
// Successfully suggested smart replies.
// ...
}
}];
]
If the operation succeeds, a SmartReplySuggestionResult
object is passed to
the completion handler. This object contains a list of up to 3 suggested
replies, which you can present to your user:
Swift
for
suggestion
in
result
.
suggestions
{
print
(
"Suggested reply:
\(
suggestion
.
text
)
"
)
}
Objective-C
for
(
FIRSmartReplySuggestion
*
suggestion
in
result
.
suggestions
)
{
NSLog
(
@
"Suggested reply: %@"
,
suggestion
.
text
);
}
Note that ML Kit might not return results if the model isn't confident in the relevance of the suggested replies, the input conversation isn't in English, or if the model detects sensitive subject matter.
