Link your Text View to your View Controller and name it as you want (let's say textView).

In viewDidLayoutSubviews function put this line:

textView.centerVertically()

Then under the last curly bracket of your class put this extension:

extension UITextView {    func centerVertically() {        let fittingSize = CGSize(width: bounds.width, height: CGFloat.greatestFiniteMagnitude)        let size = sizeThatFits(fittingSize)        let topOffset = (bounds.size.height - size.height * zoomScale) / 2        let positiveTopOffset = max(1, topOffset)        contentOffset.y = -positiveTopOffset    }   }

To use this function in Swift 2.0 just change CGFloat.greatestFiniteMagnitude to CGFloat.max

Swift 5

Put the following extension below your last curly bracket in your ViewController:

// MARK: - UITextView extensionextension UITextView {    func centerVerticalText() {        self.textAlignment = .center        let fitSize = CGSize(width: bounds.width, height: CGFloat.greatestFiniteMagnitude)        let size = sizeThatFits(fitSize)        let calculate = (bounds.size.height - size.height * zoomScale) / 2        let offset = max(1, calculate)        contentOffset.y = -offset    }}

Call this function after you set the text.

yourTextView.centerVerticalText()

If you want to do this using the storyboard, you could add a view inside of your textView. Then, set the constraints that you used for the textView to the new view. Finally, add the following constraints to your text view:

• (right and left) O and point to the new view

• using the alignment constraints, add a vertically constraint.