SelfSizing TableViewCell with Swift 2.0 Beta Raw

SelfSizingTextViewTableCell.swift

//  References
//  https://github.com/damienpontifex/BlogCodeSamples/tree/master/SelfSizingTextViewTableCell
//  https://pontifex.azurewebsites.net/self-sizing-uitableviewcell-with-uitextview-in-ios-8/
//
//  In UITableViewController 
//  tableView.rowHeight = UITableViewAutomaticDimension;
//  tableView.estimatedRowHeight = DefaultCellHeight;
//

import UIKit

extension UITableViewCell {
    /// Search up the view hierarchy of the table view cell to find the containing table view
    var tableView: UITableView? {
        get {
            var table: UIView? = superview
            while !(table is UITableView) && table != nil {
                table = table?.superview
            }
            
            return table as? UITableView
        }
    }
}

class SelfSizingTextViewTableCell: UITableViewCell {
    
    private let textView = UITextView()
    
    override init(style: UITableViewCellStyle, reuseIdentifier: String!) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)
        setup()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setup()
    }
    
    func setup(){
        
        textView.scrollEnabled = false
        textView.delegate = self
        
        contentView.addSubview(textView)
        textView.translatesAutoresizingMaskIntoConstraints = false;
        
        textView.layer.borderWidth = 1
        textView.layer.borderColor = UIColor.blackColor().CGColor
        
        //Width
        textView.superview!.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|[textView]|", options: .AlignAllCenterX, metrics: nil, views: ["textView":textView]))
        //Height
        textView.superview!.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|[textView(>=\(DefaultCellHeight))]|", options: .AlignAllTop, metrics: nil, views: ["textView":textView]))
        
    }
    
/// Custom setter so we can initialise the height of the text view
    var textString: String {
        get {
            return textView.text ?? ""
        }
        set {
            textView.text = newValue
            
            textViewDidChange(textView)
        }
    }
    override func setSelected(selected: Bool, animated: Bool) {
        super.setSelected(selected, animated: animated)

        if selected {
            textView.becomeFirstResponder()
        } else {
            textView.resignFirstResponder()
        }
    }
}

extension SelfSizingTextViewTableCell: UITextViewDelegate {
    func textViewDidChange(textView: UITextView) {
        
        let size = textView.bounds.size
        let newSize = textView.sizeThatFits(CGSize(width: size.width, height: CGFloat.max))
        
        // Resize the cell only when cell's size is changed
        if size.height != newSize.height {
            UIView.setAnimationsEnabled(false)
            tableView?.beginUpdates()
            tableView?.endUpdates()
            UIView.setAnimationsEnabled(true)
            
            if let thisIndexPath = tableView?.indexPathForCell(self) {
                tableView?.scrollToRowAtIndexPath(thisIndexPath, atScrollPosition: .Bottom, animated: false)
            }
        }
    }
}