How can I call an Objective C method from a Swift 3 app? - ios

Question

I'm trying to use wit-ai SDK, written in Objective C in a Swift 3 app.
The documentation in the GitHub repo explains how to use a particular Objective C method to send text string to Wit, but I'm not sure how to use that method in my app, and could use some guidance.
InterpretString
Sends an NSString to wit.ai for interpretation. Same as sending a voice input, but with text.
- (void) interpretString: (NSString *) string customData:(id)customData;
This is what I have so far:
import UIKit
class ViewController: UIViewController, WitDelegate {
/**
* Called when the Wit request is completed.
* param outcomes a NSDictionary of outcomes returned by the Wit API. Outcomes are ordered by confidence, highest first. Each outcome contains (at least) the following keys:
* intent, entities[], confidence, _text. For more information please refer to our online documentation: https://wit.ai/docs/http/20141022#get-intent-via-text-link
*
* param messageId the message id returned by the api
* param customData any data attached when starting the request. See [Wit sharedInstance toggleCaptureVoiceIntent:... (id)customData] and [[Wit sharedInstance] start:... (id)customData];
* param error Nil if no error occurred during processing
*/
public func witDidGraspIntent(_ outcomes: [Any]!, messageId: String!, customData: Any!, error e: Error!) {
if ((e) != nil) {
print("\(e.localizedDescription)")
return
}
let outcomes : NSArray = outcomes! as NSArray
let firstOutcome : NSDictionary = outcomes.object(at: 0) as! NSDictionary
let intent : String = firstOutcome.object(forKey: "intent") as! String
labelView!.text = intent
labelView!.sizeToFit()
}
var labelView : UILabel?
var witButton : WITMicButton?
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
// set the WitDelegate object
Wit.sharedInstance().delegate = self
// create the button
let screen : CGRect = UIScreen.main.bounds
let w : CGFloat = 100
let rect : CGRect = CGRect(x: screen.size.width/2 - w/2, y: 60, width: w, height: 100)
witButton = WITMicButton(frame: rect)
self.view.addSubview(witButton!)
// create the label
labelView = UILabel(frame: CGRect(x: 0, y: 200, width: screen.size.width, height: 50))
labelView!.textAlignment = .center
labelView!.text = "intent"
labelView!.textColor = UIColor.black
labelView!.sizeToFit()
self.view.addSubview(labelView!)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}