how can i increase the height of an inputAccessoryView

To make input accessory view grow vertically you just set its autoresizingMask = .flexibleHeight, calculate its intrinsicContentSize and let the framework do the rest.

The code:

class InputAccessoryView: UIView, UITextViewDelegate {    let textView = UITextView()    override init(frame: CGRect) {        super.init(frame: frame)        // This is required to make the view grow vertically        self.autoresizingMask = UIView.AutoresizingMask.flexibleHeight        // Setup textView as needed        self.addSubview(self.textView)        self.textView.translatesAutoresizingMaskIntoConstraints = false        self.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[textView]|", options: [], metrics: nil, views: ["textView": self.textView]))        self.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[textView]|", options: [], metrics: nil, views: ["textView": self.textView]))        self.textView.delegate = self        // Disabling textView scrolling prevents some undesired effects,        // like incorrect contentOffset when adding new line,        // and makes the textView behave similar to Apple's Messages app        self.textView.isScrollEnabled = false    }    required init?(coder aDecoder: NSCoder) {        fatalError("init(coder:) has not been implemented")    }    override var intrinsicContentSize: CGSize {        // Calculate intrinsicContentSize that will fit all the text        let textSize = self.textView.sizeThatFits(CGSize(width: self.textView.bounds.width, height: CGFloat.greatestFiniteMagnitude))        return CGSize(width: self.bounds.width, height: textSize.height)    }    // MARK: UITextViewDelegate    func textViewDidChange(_ textView: UITextView) {        // Re-calculate intrinsicContentSize when text changes        self.invalidateIntrinsicContentSize()    }}

Fast forward to 2020, you can just do the following, everything else the same as in maxkonovalov's answer

override var intrinsicContentSize: CGSize {    return .zero}// MARK: UITextViewDelegatefunc textViewDidChange(_ textView: UITextView) {    sizeToFit()}