Swift 使用AttributedString截断跟踪

我在单元格中有一个UILabel，我正在其中设置属性文本。它的属性文本太大，超出了它应有的大小。。。最后。怎么做

func addTitle(title: String) {
    let paragraphStyle = NSMutableParagraphStyle()
    paragraphStyle.lineBreakMode = .byTruncatingTail
    let attributedTitle = NSAttributedString(string: title, attributes: [NSParagraphStyleAttributeName: paragraphStyle])
    self.titleLabel.attributtedString = attributedTitle
}