CustomTableViewCell Auto Layout programmatically

import UIKit

class CustomTableViewCell: UITableViewCell
{
    var contentText:String = "";
    var contentLabel = UILabel();
  
    override func awakeFromNib() {
        super.awakeFromNib()
    }

    override init(style: UITableViewCellStyle, reuseIdentifier: String!)
    {
        super.init(style: style, reuseIdentifier: reuseIdentifier)
        self.contentLabel.translatesAutoresizingMaskIntoConstraints = false
        contentLabel.backgroundColor=UIColor.cyanColor()
        contentLabel.font = UIFont.systemFontOfSize(22)
        contentLabel.sizeToFit()
        contentLabel.numberOfLines = 0
        self.addSubview(contentLabel);
        self.ajustAutoLayout()
    }
    
    func ajustAutoLayout()  {
        
        let top = NSLayoutConstraint(item: self.contentLabel,
                                       attribute: NSLayoutAttribute.Top,
                                       relatedBy: NSLayoutRelation.Equal,
                                       toItem: self,
                                       attribute: NSLayoutAttribute.Top,
                                       multiplier: 1.0,
                                       constant: 30)
        
        let bottom = NSLayoutConstraint(item: self.contentLabel,
                                        attribute: NSLayoutAttribute.Bottom,
                                        relatedBy: NSLayoutRelation.Equal,
                                        toItem: self,
                                        attribute: NSLayoutAttribute.Bottom,
                                        multiplier: 1.0,
                                        constant: -30)
        
        let left = NSLayoutConstraint(item: self.contentLabel,
                                       attribute: NSLayoutAttribute.Leading,
                                       relatedBy: NSLayoutRelation.Equal,
                                       toItem: self,
                                       attribute: NSLayoutAttribute.Leading,
                                       multiplier: 1.0,
                                       constant: 50)
        
        let right = NSLayoutConstraint(item: self.contentLabel,
                                       attribute: NSLayoutAttribute.Trailing,
                                       relatedBy: NSLayoutRelation.Equal,
                                       toItem: self,
                                       attribute: NSLayoutAttribute.Trailing,
                                       multiplier: 1.0,
                                       constant: -50)
        self.addConstraint(top)
        self.addConstraint(bottom)
        self.addConstraint(left)
        self.addConstraint(right)
    }
   
    func setContentLabelText(text:String){
        let textFontStyle: String = "Helvetica"
        let textFontSize: CGFloat = 20.5
        let textFont = UIFont(name: textFontStyle, size: textFontSize)!
        let textStyle = NSMutableParagraphStyle()
        textStyle.lineSpacing = 18.0
        textStyle.paragraphSpacing = 18.0
        textStyle.alignment = NSTextAlignment.Justified
        let attributes: Dictionary = [NSParagraphStyleAttributeName: textStyle, NSFontAttributeName: textFont]
        let attibute = NSAttributedString(string:text, attributes: attributes)
        self.contentLabel.attributedText = attibute
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("error")
    }
    
}

class CustomTableSandBox: UIViewController, UITableViewDelegate, UITableViewDataSource {
    
    private var tableView: UITableView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        tableView = UITableView(frame: CGRect(x: 0, y:0, width: self.view.frame.width, height:self.view.frame.height))
        tableView.dataSource = self
        tableView.delegate = self
        tableView.estimatedRowHeight = 500
        tableView.rowHeight = UITableViewAutomaticDimension
        tableView.registerClass(CustomTableViewCell.self, forCellReuseIdentifier: "customCell")
        self.view.addSubview(tableView)
    }

    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return 10
    }
 
    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCellWithIdentifier("customCell", forIndexPath: indexPath) as! CustomTableViewCell
        let text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.";
        cell.setContentLabelText(text);
        cell.accessoryType = UITableViewCellAccessoryType.DisclosureIndicator
        return cell
    }
    
    override func viewWillAppear(animated: Bool) {
        tableView.reloadData()
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

}