在Swift中向属性文本添加属性

Question

我尝试将属性添加到文本标签：

let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.alignment = NSTextAlignment.Center

let para = NSMutableAttributedString()
let font:UIFont? = UIFont(name: "DIN Alternate", size: 18.0)
let font2:UIFont? = UIFont(name: "Arial", size: 12.0)
let labelColor = UIColor.whiteColor()
let text="some text"

//A, error appears here
let myAttributes = [NSParagraphStyleAttributeName:paragraphStyle,
                    NSFontAttributeName:font,
                    NSForegroundColorAttributeName:labelColor]

let attrString = NSAttributedString(
    string: csvObject.provideDetailsAsString(poi)!,
    attributes: myAttributes)
para.appendAttributedString(attrString)     
detailsText.attributedText = para

但是在//行A中的Swift编译器错误并说：

'_' is not convertible to 'String'

我正在使用XCode 6.4和Swift 1.2

Answer 1

找到它，加一个！在 font 之后：NSFontAttributeName：font！

字体是可选