Upvote:2

Aprove answer 
override func viewDidLoad() {
    super.viewDidLoad()
    
    customTextView.other = self
}

Upvote:0 

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var customTextView: CustomTextView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        customTextView.callback = { 
           print("ViewController delegate textViewDidChange")
        }
    }
}

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