Subscribe to receive in-app messages. The subscriber callback will be called whenever a new in-app message is triggered. This method should be called before calling [[openSession]].
openSession
The callback function to handle the in-app message. This function will be called with an [[InAppMessage]] or a [[ControlMessage]] object.
InAppMessage
ControlMessage
The identifier of the subscription created. Returns undefined if the SDK has not been initialized.
Subscribe to receive in-app messages. The subscriber callback will be called whenever a new in-app message is triggered. This method should be called before calling [[
openSession]].