Written by Linh Vo
on May 11, 2017

Autoresizing UITextView Like in Messaging Apps

Today we are going to learn how we can resize our UITextView so it fits its content and after it takes a big chunk of text it cannot longer become bigger and it starts scrolling.

The first thing we need to do is to give our textView a height constraint, you can do it in storyboard but also in code writing the next line:

textView.heightAnchor.constraint(equalToConstant: 52.0).isActive = true

After that we need to confirm to the UITextFieldDelegate by writing the following line:

textView.delegate = self

Now we will create an extension for this delegate. And the function we are going to use is textViewDidChange(_ textView: UITextView)

extension ViewController: UITextViewDelegate {

    func textViewDidChange(_ textView: UITextView) {

        let size = CGSize(width: textView.frame.size.width, height: .infinity)
        let estimatedSize = textView.sizeThatFits(size)

        guard textView.contentSize.height < 100.0 else {
            textView.isScrollEnabled = true
            return
        }

        textView.isScrollEnabled = false
        textView.constraints.forEach { (constraint) in
            if constraint.firstAttribute == .height {
                constraint.constant = estimatedSize.height
            }
        }
    }
}

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