从UITextView Swift 2获取文本

我正在使用swift 2做一个iOS项目，我有一个带有自定义单元格的UITableView。我有一个带有UITextView和简单标签的单元格，修改后我不想获得此UITextView的值，但它与UITextFields不同，我不能在edit begin方法上使用。我怎样才能做到这一点 ？

这是定义我的自定义单元格的代码：

let cell = tableView.dequeueReusableCellWithIdentifier(CurrentFormTableView.CellIdentifiers.ParagraphCell, forIndexPath: indexPath) as! ParagraphCell
                cell.display(block)
                cell.selectionStyle = UITableViewCellSelectionStyle.None
                tableView.rowHeight = UITableViewAutomaticDimension
                tableView.estimatedRowHeight = 160.0
                return cell

这是我的ParagraphCell.swift

import UIKit

protocol ParagraphCell {
    func update ParagraphCell(cell: ParagraphCell, rep: String)
}

class ParagraphCell: UITableViewCell {

    @IBOutlet weak var titleLabel: UILabel!
    @IBOutlet weak var answerField: UITextView!


    var delegate: ParagraphCell Delegate?

    override func awakeFromNib() {
        super.awakeFromNib()
        // Initialization code
        let borderColor : UIColor = UIColor(red: 0.85, green: 0.85, blue: 0.85, alpha: 1.0)
        answerField.layer.borderWidth = 0.5
        answerField.layer.borderColor = borderColor.CGColor
        answerField.layer.cornerRadius = 5.0

    }

    override func setSelected(selected: Bool, animated: Bool) {
        super.setSelected(selected, animated: animated)

        // Configure the view for the selected state
    }

    func display(block: Block){
        titleLabel.text = block.title
        answerField.text = ""
    }

//THIS METHOD IS NEVER CALLED... 
    func textViewDidChange(textView: UITextView) { //Handle the text changes here
        print(textView.text); //the textView parameter is the textView where text was changed
        delegate?.update ParagraphCell(self, rep: textView.text)
    }


}