title: What sorts of problems cause Core Text crashes in calls to `sizeThatFits`?
body: <p>I've seen a handful of different crash reports coming in that all seem to be triggered when Core Text is calculating the size of some text in response to a call to <code>[UIView sizeThatFits]</code>.  I suspect the crashes share some common cause, but I've only got a few stack traces and I don't know how to reproduce any of the problems myself, so I'm left guessing what sorts of problems could be triggering the crash.</p>
  
  <p>In one case the crash is happening in an <code>ABPeoplePickerNavigationController</code> and the code on the stack is entirely Apple code. I've audited my code to make sure that UIKit/Core Text are only being used from the main thread.</p>
  
  <p>I saw this <a href="http://www.buzztouch.com/forum/thread.php?tid=A6CED5564801953BA0E93B7&amp;currentPage=1" rel="nofollow">tantalizing stack trace</a> posted on the buzztouch forum, which looks very similar and also shares the "contacts" trigger.</p>
  
  <pre><code>frame #0: 0x007fe283 CoreText`TComponentFont::GetMinSideBearing(CGAffineTransform const&amp;, bool) const + 43 
  frame #1: 0x0076b244 CoreText`TRun::GetLeftHangersGlyphCountAndWidth(long, unsigned long, TCharStream const&amp;) const + 524 
  frame #2: 0x0077e7da CoreText`TLine::GetLeftHangersGlyphCountAndWidth(unsigned long const*) const + 234 
  frame #3: 0x0077e4b9 CoreText`TLine::GetBounds(unsigned long) const + 811 
  frame #4: 0x0077ace6 CoreText`CTLineGetBoundsWithOptions + 44 
  frame #5: 0x02059497 UIKit`-[UITableViewIndex _cacheAndMeasureTitles] + 984 
  frame #6: 0x02059ace UIKit`-[UITableViewIndex sizeThatFits:] + 131
  </code></pre>
  
  <p>On the forum, someone named Ofer left a post saying the crash had been fixed.  I'm hoping Ofer might be kind enough to share some details about what they discovered they were doing to trigger the crash!</p>