Unable to compile Siri extension in Swift 2.3 - swift

Question

I want to integrate the Siri/Intent extension in my App, currently based on Swift 2.3. I am using the Xcode 8 beta 6 build.
The app fails to even compile, giving out errors as
Type 'IntentHandler' does not conform to protocol 'INSendMessageIntentHandling'
Protocol requires function 'handle(sendMessage:completion:)' with type '(sendMessage: INSendMessageIntent, completion: (INSendMessageIntentResponse) -> Void) -> Void'
Objective-C method 'handleWithSendMessage:completion:' provided by method 'handle(sendMessage:completion:)' does not match the requirement's selector ('handleSendMessage:completion:')
Even the sample app from Apple, UnicornChat fails to compile with the same errors. I did change the SWIFT_VERSION flag to Yes, to support Swift 2.3
Sample Code:
func handle(sendMessage intent: INSendMessageIntent, completion: (INSendMessageIntentResponse) -> Void) {
let userActivity = NSUserActivity(activityType: NSStringFromClass(INSendMessageIntent.self))
let response = INSendMessageIntentResponse(code: .Success, userActivity: userActivity)
completion(response)
}
This fails with the error above.
Anyone has an idea on how to make Siri work in Swift 2.3?

Answer 1

So, this helped
https://forums.developer.apple.com/message/174455#174455
We need to explicitly define the #objc method signatures with the Swift ones. As in the following works.
#objc (handleSendMessage:completion:)
func handle(sendMessage intent: INSendMessageIntent, completion: (INSendMessageIntentResponse) -> Void) {
//..
}

Answer 2

Apparently Xcode 8 beta 6 has been updated to Swift 3 and the call back needs #escaping added to the method:
func handle(sendMessage intent: INSendMessageIntent, completion: #escaping (INSendMessageIntentResponse) -> Swift.Void) {
//..
}
If the Siri delegate methods have been updated to Swift 3 (as appears to be the case) then I am afraid you will have to use Swift 3 as well, or an older version of the SDK.

Answer 3

While compiling your code with Swift 2.3, you need to set Use Legacy Swift Language Version to YES for Siri and SiriUI targets.
Also, when IntentHandler and IntentViewController are created, methods might have been created in Swift 3 (as happened to me). So convert the classes to Swift 2.3, and use #objc method signatures along with the delegates.
For IntentHandler,
#objc (handleSendMessage:completion:)
func handle(sendMessage intent: INSendMessageIntent, completion: (INSendMessageIntentResponse) -> Void) {
}
#objc (handleSearchForMessages:completion:)
func handle(searchForMessages intent: INSearchForMessagesIntent, completion: (INSearchForMessagesIntentResponse) -> Void) {
}
#objc (handleSetMessageAttribute:completion:)
func handle(setMessageAttribute intent: INSetMessageAttributeIntent, completion: (INSetMessageAttributeIntentResponse) -> Void) {
}
For IntentViewController,
#objc (configureWithInteraction:context:completion:)
func configureWithInteraction(interaction: INInteraction!, context: INUIHostedViewContext, completion: ((CGSize) -> Void)!) {
}
Hope this helped.