滚动时Swift致命错误

Question

试。

我的小项目有问题。

它会运行，但如果我尝试向下滚动它会崩溃！

带有致命错误的代码部分是：

  func fontForDisplay(atIndexPath indexPath: NSIndexPath) -> UIFont? {
    if indexPath.section == 0 {
        let familyName = familyNames[indexPath.row]
        let fontName = UIFont.fontNamesForFamilyName(familyName).first! as String
        return UIFont(name: fontName, size: cellPointSize)
    } else {
        return nil
    }
}

你能帮助我吗？

谢谢！

Answer 1

我猜投降失败，如果让

包裹它

if let fontName = UIFont.fontNamesForFamilyName(familyName).first as? String{
   return UIFont(name: fontName, size: cellPointSize)
}

Answer 2

let fontName = UIFont.fontNamesForFamilyName(familyName).first

as String！ 或

let fontName : String! = UIFont.fontNamesForFamilyName(familyName).first