Crash reported parsing markdown

[tsfischer]

We have had a significant number of crashes reported from the field via Crashlytics. The crash is:
Fatal Exception: NSInvalidArgumentException
*** -[__NSPlaceholderDictionary initWithObjects:forKeys:count:]: attempt to insert nil object from objects[0]

and the call stack looks like:
Fatal Exception: NSInvalidArgumentException
0 CoreFoundation 0x7fffc5cb72b3 (Missing)
1 libobjc.A.dylib 0x7fffdaace48d (Missing)
2 CoreFoundation 0x7fffc5bb43f0 (Missing)
3 CoreFoundation 0x7fffc5bb425b (Missing)
4 TSMarkdownParser 0x10a1707ad (Missing)
5 TSMarkdownParser 0x10a170991 (Missing)
6 Self Service 0x109af1fde specialized SSHistoryContentCellView.(content.didset).(closure #1) (SSHistoryContentCellView.swift:37)

Here is the SSHistoryContentCellView code in question:

              let attrDescription = TSMarkdownParser.standard().attributedString(fromMarkdown: self.content.jssDescription ?? "", attributes: [NSAttributedStringKey.foregroundColor.rawValue : NSColor.descriptionTextColor()])
                self.descriptionLabel.isHidden = attrDescription.length == 0
                self.descriptionLabel.textStorage?.setAttributedString(attrDescription)
                self.descriptionHeightConstraint.constant = self.self.descriptionLabel.heightForString()

Looking at the pod code and our own code, the only usage of NSDictionary is for the attributes. But I am passing in a constant for the attributes dictionary, so that should never go null. I am at a loss of what might be causing this, and I am unable to reproduce it in-house.

[Coeur]

@tsfischer Can you confirm that:

• it's macOS? (and not iOS/tvOS)
• it's TSMarkdownParser 2.1.3?
• it's Swift 4.0/Xcode 9.2?

Can you give more details about the value of [NSAttributedStringKey.foregroundColor.rawValue : NSColor.descriptionTextColor()]?

[tsfischer]

Thanks much for your response. Since writing this post, I discovered that our customer was deleting all fonts from the /Library/Fonts folder and that was causing this crash. They are a publishing house and want to clear out this folder for copyright reasons.

For the short term, we told them to put fonts back until the crash goes away... but it would be nice if TSMarkdownParser wouldn't crash if it encounters a missing font.

As a note, they aren't actually using markdown... so only normal strings (no markdown tags) are being used and no additional fonts requested.

[Coeur]

I'll be working on TSMarkdownParser today, so it's your chance. But I need a way to reproduce the issue. You're mentioning fonts, but the code you gave is about foregroundColor only. Also can you specify the macOS Deployment Target? Is it 10.9, 10.10, 10.11, 10.12 or 10.13?

[Coeur]

I tried this:

let attrDescription = TSMarkdownParser.standard()
                        .attributedString(fromMarkdown: "SSHistoryContentCellView text",
                          attributes: [NSAttributedStringKey.foregroundColor.rawValue : NSColor.blue])
print(attrDescription)

And I got a correct print with no crash:

SSHistoryContentCellView text{
NSColor = "sRGB IEC61966-2.1 colorspace 0 0 1 1";
}

But we have font usage when dealing with:

• headerAttributes (i.e. "# hello")
• quoteAttributes (i.e. "> hello")
• monospaceAttributes (i.e. "hello")
• strongAttributes (i.e. "hello")
• emphasisAttributes (i.e. "hello")

So I tried:

let attrDescription = TSMarkdownParser.standard()
                        .attributedString(fromMarkdown: "# hello\n> hello\n`hello` __hello__ _hello_",
                          attributes: [NSAttributedStringKey.foregroundColor.rawValue : NSColor.blue])
print(attrDescription)

But I still didn't get any crash on macOS High Sierra (10.13.3). Please help to reproduce the issue, @tsfischer. And if you're removing a font from the app, then you should overwrite the default settings from the app that were using this font:

    TSMarkdownParser.standard().headerAttributes = [[:]]// or whatever you want
    TSMarkdownParser.standard().quoteAttributes = [[:]]// or whatever you want
    TSMarkdownParser.standard().monospaceAttributes = [:]// or whatever you want
    TSMarkdownParser.standard().strongAttributes = [:]// or whatever you want
    TSMarkdownParser.standard().emphasisAttributes = [:]// or whatever you want

[Coeur]

Oh, OK, I start to understand. If you remove HelveticaNeue-Italic from the system, then this simple call will create a crash:

let parser = TSMarkdownParser.standard()

And this will be caused by:

_quoteAttributes = @[@{NSFontAttributeName: [UIFont fontWithName:@"HelveticaNeue-Italic" size:defaultSize]}];

I'll workaround this.

[Coeur]

Fixed in 2.1.4

[Coeur]

Actually a duplicate of #58