I want to create chatter post with mention for API version 37.0
Have a look over this link Chatter Api Saying
Feed item methods aren’t available in version 32.0. In version 32.0 and later, use feed element methods.
postFeedElement(communityId, feedElement, feedElementFileUpload) this method supported API Version is 31.0–35.0
In version 36.0 and later, this method is no longer available because you can’t create a feed post and upload a binary file in the same call. Upload files to Salesforce first, and then use postFeedElement(communityId, feedElement) to create the feed post and attach the files.
How to create chatter post with mention for API version 37.0??