MacDownApp/macdown

Crash when scrolling on initial Markdown preview render (MacOS Sierra)

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#716 opened on Dec 23, 2016

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 (7 comments) (0 reactions) (0 assignees)Objective-C (7,686 stars) (930 forks)batch import
bughelp wanted

Description

I noticed today that when I opened a rather large Markdown file in Macdown, and tried to scroll down immediately, before the preview finished rendering, the application would crash. This happened a couple of times, also with some smaller files. I successfully managed to replicate it just before writing this report (to get the crash log). It seems to be an issue with the main view trying to scroll the preview view before it has any content. Here is an image of the crash log: image

Here is the full log: http://pastebin.com/EenjhawV

Contributor guide

Tech stack
objective c
Domain
desktop
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Objective CmacOS developmentdebugging with Xcode
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50
Research direction
The crash occurs when scrolling the preview before it's fully rendered, likely due to a nil content view. Investigate the preview rendering lifecycle in MacDown's source code, specifically the methods handling scroll and content updates. Look for where the preview view's content is set and ensure that scrolling is prevented or deferred until content is available. Check the crash log in the issue for exact stack trace to identify the class and method causing the crash.