使用NSMutableAttributedString在Swift中的UITextView中的粗体文本

Question

I'm trying to bold part of a text in a UITextView. Here is the code I'm using (though I simplified the text):

@IBOutlet weak var textview: UITextView!

/*...*/

var str : NSMutableAttributedString = NSMutableAttributedString(string:"this is a test", attributes: [NSFontAttributeName:textview.font!] )
str.addAttribute(NSFontAttributeName, value: UIFont(name: "GillSans-Bold", size: 16)!, range: NSMakeRange(10, 4))
textview.attributedText = str

However it is not working and I don't understand why... All the examples I've seen use this. There is no error, but nothing in the text is in bold.

Sorry if it's a duplicate, I found plenty of posts talking about putting text in bold in a uitextview, some used this technique but none had problems with it, as far as I know. Is there something I missed? Did I read something wrong?

Thanks in advance.

Answer 1

One reason might be that the font you're using doesn't exist or is not properly named in the code. Here's a neat trick to show the list of all available fonts:

//credits to Chris: http://codewithchris.com/common-mistakes-with-adding-custom-fonts-to-your-ios-app/#includefonts
func printFontFamilyNames(){

    for family: String in UIFont.familyNames()
    {
        print("\(family)")
        for names: String in UIFont.fontNamesForFamilyName(family)
        {
            print("== \(names)")
        }
    }

}

This may not directly answer your question but I'm sure you'll find it helpful. And also check the link on the top of this code block, from which I've extracted this function.

UPDATE

Here's a piece of code I wrote, which properly changes the font of attributed strings within a UILabel :

if let terms = self.terms {

        let text = NSMutableAttributedString(string: terms.text!)

        let textAsString = text.string as NSString
        let range = NSMakeRange(0, textAsString.length)

        textAsString.enumerateSubstringsInRange(range, options: NSStringEnumerationOptions.ByWords, usingBlock: { (substring, substringRange, enclosingRange, _) -> () in

            if  ["Create", "Account", "Terms", "of", "Service", "Privacy", "policy"].contains(substring!) {

                if let font = UIFont(name: "OpenSans-Semibold", size: 11) {

                    text.addAttribute(NSFontAttributeName, value: font, range: substringRange)

                } else {

                    Services.log("Invalid font")

                }

            }

            //...

        })

        terms.attributedText = text

    }

NOTE: This code contains project specific classes and variables, but I'm sure you can extract what you need.