UItextView delegate swift - textViewDidBeginEditing not called

I've seen the other topics dealing with UITextView delegate, but can't seem to find where my issue come from. Here is my code, but when I modify my UITextView, nothing happens and textViewDidBeginEditing is not called.

import UIKit
var textView1 = UITextView()

class ViewController: UIViewController, UITextViewDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()

        textView1.delegate = self
        textView1 = UITextView(frame: CGRect(x:24,y: 100,width: 340,height: 290))
        textView1.textColor = UIColor.black
        textView1.backgroundColor = UIColor(red: 0.00, green: 0.00, blue: 0.00, alpha: 0.00)
        textView1.text = "textView 1"
        view.addSubview(textView1)
    }

    func textViewDidBeginEditing(_ textView: UITextView) {
        print("print1")
    }

    func textViewDidEndEditing(_ textView: UITextView) { 
        print("print2")
    }
}

I've tried with UITextField, but nothing changed, delegate functions still not called.