使用旧金山字体将HTML解析为NSAttributedString？(iOS 9)

Question

我需要解析包含<b>(粗体),<i>(斜体)和<u>(下划线)标签的基本HTML字符串,没有别的,只是那些简单的标签.

现在,我只能得到<u>(下划线)标签在正确渲染NSAttributedString,使用新的时San Francisco中iOS 9.

我真的需要得到<b>(粗体)和<i>(斜体)渲染.

这是我正在做的事情:

let text = "<i>Any</i> <b>Text</b> <u>that's basic HTML</u>"
let font = UIFont.preferredFontForTextStyle(UIFontTextStyleBody)

let modifiedFont = NSString(format:"<span style=\"font-family: '-apple-system','HelveticaNeue'; font-size: %f \">%@</span>",
font.pointSize, text) as String

let data = (modifiedFont as NSString).dataUsingEncoding(NSUTF8StringEncoding)

let attributedString = try? NSAttributedString(data: data!, options:
            [ NSDocumentTypeDocumentAttribute : NSHTMLTextDocumentType,
                NSCharacterEncodingDocumentAttribute : NSUTF8StringEncoding,
                NSFontAttributeName : font ],
            documentAttributes: nil)

但不幸的是,<i>(斜体)和<b>(粗体)标签永远不会渲染,只有<u>(下划线)正确渲染.

这个相同的方法用于iOS 8处理Helvetica-Neue字体,但它不适用于新iOS 9 San Francisco字体

帮助我<b>(粗体)和<i>(斜体)正确渲染NSAttributedString!

更新:我也在整个应用程序中使用动态文本.这可能是事情不起作用的原因......

Answer 1

在应用程序中同时使用NSAttributedString和DynamicType是导致问题的原因。

事实证明，你NEED重新解析/渲染你String收到后UIContentSizeCategoryDidChangeNotification。您不能保留NSAttributedString，然后使用它来重置UILabel. 您必须重新解析/渲染NSAttributedString.

简要示例：

public override func viewDidLoad() {
    super.viewDidLoad()

    //register be notified when text size changes.
    NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("didChangePreferredContentSize:"), name: UIContentSizeCategoryDidChangeNotification, object: nil)
}

// The action Selector that gets called after the text size has been changed.
func didChangePreferredContentSize(notification: NSNotification) {
    self.myLabel.font = UIFont.preferredFontForTextStyle(UIFontTextStyleSubheadline)
    //
    // DO NOT do this:
    // self.myLabel.attributedText = self.myAlreadyRenderedText
    //
    //Make sure you re-render/parse the text into a new NSAttributedString.
    //Do THIS instead:
    self.myLabel.attributedText = self.renderAttributedText(str)
}

//Our method to render/parse the HTML tags in our text. Returns an NSAttributedString.
func renderAttributedText(str: String) -> NSAttributedString? {
    let text = "<i>Any</i> <b>Text</b> <u>that's basic HTML</u>"
    let font = UIFont.preferredFontForTextStyle(UIFontTextStyleBody)

    let modifiedFont = NSString(format:"<span style=\"font-family: '-apple-system','HelveticaNeue'; font-size: %f \">%@</span>",font.pointSize, text) as String

    let data = (modifiedFont as NSString).dataUsingEncoding(NSUTF8StringEncoding)

    let attributedString = try? NSAttributedString(data: data!, options:
        [ NSDocumentTypeDocumentAttribute : NSHTMLTextDocumentType,
            NSCharacterEncodingDocumentAttribute : NSUTF8StringEncoding,
            NSFontAttributeName : font ],
        documentAttributes: nil)

    return attributedString
}

deinit {
    NSNotificationCenter.defaultCenter().removeObserver(self)
}