swift – 设置NSUnderlineStyle会导致无法识别的选择器异常

我试图用NSAttributed字符串为字符串加下划线.由于某种原因,我的行导致异常：

-[_SwiftValue _getValue:forType:]: unrecognized selector sent to instance

结果应该用于UITableView中的UILabel,并根据需要创建.

这是代码：

attributedString = NSMutableAttributedString(string: message)

if let actor = event.actor {
   let attributes = [NSUnderlinestyleAttributeName:NSUnderlinestyle.styleSingle]
   var attributedActorString = NSMutableAttributedString(string: actor.shirtName,attributes: attributes)
   attributedActorString.insert(NSAttributedString(string: " "),at: 0)
   attributedActorString.append(NSAttributedString(string: ". "))                               attributedActorString.append(attributedImageStringForUrl(event.actor!.portraitimageUrl,indexPath: indexPath))
   attributedString.append(attributedActorString)
}

换线：

let attributes = [NSUnderlinestyleAttributeName:NSUnderlinestyle.styleSingle]

至：

let attributes = [NSUnderlinestyleAttributeName:NSUnderlinestyle.styleSingle.rawValue]