Setting font size doesn't work after parsing simple HTML into NSAttributedString

Question

I want to parse simple HTML markup into a NSAttributedString so that I can display formatted text on an UITextView. I found this and that post where it should be easy to convert. That is what I've used:

public static NSAttributedString GetAttributedStringFromHtml(string html)
{
    NSError error = null;
    NSAttributedString attributedString = new NSAttributedString (NSData.FromString(html), 
        new NSAttributedStringDocumentAttributes{ DocumentType = NSDocumentType.HTML, StringEncoding = NSStringEncoding.UTF8 }, 
        ref error);
    return attributedString;
}

This is working so far, but now I want to change the font size, because the default one is very small.

string content = "<strong>I'm strong.</strong><br/>http://www.google.com";

UITextView textView = new UITextView ();
textView.Editable = false;
textView.Font = UIFont.SystemFontOfSize (25);
textView.Text = content;
textView.AttributedText = GetAttributedStringFromHtml (content);
textView.DataDetectorTypes = UIDataDetectorType.Link;
textView.Selectable = true;

The code above does parse it correctly, but the font size isn't changed. I tried to use NSMutableAttributedString, but it seems that it takes no NSData as argument for parsing like the NSAttributedString does. Perhaps it would be an option to combine multiple NSAttributedString, but I don't know how. Another option would be to cast like this example:

NSMutableAttributedString attributedString = (NSMutableAttributedString) GetAttributedStringFromHtml (content);
attributedString.AddAttribute (UIStringAttributeKey.Font, UIFont.SystemFontOfSize (25), new NSRange (0, content.Length));
textView.AttributedText = attributedString;

but I get System.InvalidCastException.

How can I change the font size of the UITextView even if I use the HTML parsing?

Edit:

Now I tried to create my NSMutableAttributedString:

NSAttributedString parsedString = GetAttributedStringFromHtml (content);
NSMutableAttributedString attributedString = new NSMutableAttributedString (parsedString);
attributedString.AddAttribute (UIStringAttributeKey.Font, UIFont.SystemFontOfSize (17), new NSRange (0, attributedString.Length));
textView.AttributedText = attributedString;

This does compile, the font size is bigger and also the HTML is parsed, but it ignorses the <strong> for example. The text isn't bold, where it should be. It seems that the second attribute overwrites the first one ...

Answer 1

I tried a few things but none of them worked. So I'm already parsing the HTML why not use inline CSS syntax?

<p style='font-size:17px'><strong>I'm bold.</strong><br/>http://www.google.com</p>