更改NSAttributedString的字體大小

Question

我的應用程序從網站上獲取了一些HTML格式的文本，我想更改NSAttributedString的字體大小並將其顯示在textview中

var htmlString : String //the html formatted text
textView.attributedText = handleHtml(htmlString) // this is how I call the function, but the font size didn't change

func handleHtml(string : String) -> NSAttributedString{
    let attrs = [ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType, NSFontAttributeName: UIFont.systemFontOfSize(20.0)]
    var returnStr = NSAttributedString()
    do {
        returnStr = try NSAttributedString(data: string.dataUsingEncoding(NSUnicodeStringEncoding, allowLossyConversion: true)!, options: attrs, documentAttributes: nil)
    } catch {
        print(error)
    }
    return returnStr
}

如上面的代碼所示，我嘗試了[NSFontAttributeName: UIFont.systemFontOfSize(20.0)] ，但是字體大小沒有變化。

Answer 1

我只是想通了。 我應該使用NSMutableAttributedString而不是NSAttributedString

func handleHtml(string : String) -> NSAttributedString{
    var returnStr = NSMutableAttributedString()
    do {
        returnStr = try NSMutableAttributedString(data: string.dataUsingEncoding(NSUnicodeStringEncoding, allowLossyConversion: true)!, options: [ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType], documentAttributes: nil)

        let fullRange : NSRange = NSMakeRange(0, returnStr.length)
        returnStr.addAttributes([NSFontAttributeName : yourFont], range: fullRange)

    } catch {
        print(error)
    }
    return returnStr
}