EXC_BAD_ACCESS on NSString sizeWithFont - objective-c

Question

I am not sure what is going on anymore. I have tried so many things to for me to figure out whats going on on this specific line of code that is causing a EXC_BAD_ACCESS.
I tried enabled NSZombies but it didn't help me any. Here is the code:
- (int)linesFromText:(NSString *)string withFont:(UIFont *)font andSize:(CGSize)size {
NSArray *splitString = [string componentsSeparatedByString:#" "];
NSMutableArray *allLines = [NSMutableArray array];
NSMutableString *line = [NSMutableString string];
NSString *word;
NSString *fakeLine;
for (int i = 0; i < splitString.count; i++) {
word = [splitString objectAtIndex:i];
fakeLine = [NSString stringWithFormat:#"%#%# ",line, word];
//NSLog(#"line %#, font %#",fakeLine,font);
////THIS IS THE LINE CAUSING THE EXC_BAD_ACCESS
CGSize lineSize = [fakeLine sizeWithFont:font];
if (lineSize.width <= size.width) {
[line appendFormat:#"%# ", word];
} else {
[allLines addObject:[line stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]]];
line = [NSMutableString string];
[line appendFormat:#"%# ", word];
}
}
[allLines addObject:[line stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]]];
return allLines.count;
}
This is driving me crazy cause it only happens on the new iphone 5 when you scroll through the days to fast in the app I built. Here is a link to the application in the store:
http://itunes.apple.com/us/app/id543324451?mt=8
if you have an iphone 5 you can see what I mean. iphone 4 doesn't do this.
This code is being called in a UITableViewCell's layoutSubviews and is there to help size the frame of a Custom Attributed label that uses TTTAttributedLabel (https://github.com/mattt/TTTAttributedLabel).
I also tried to enable "Gaurd malloc to try give me more details but my XCode gives me this error:
dyld: could not load inserted library '/usr/lib/libgmalloc.dylib' because image not found
which if I look in /usr/lib that file is a sym link to a file that does exist in the same directory:
libgmalloc.dylib -> libgmalloc.B.dylib
I am running out of ideas here and thought it might be the UIFont getting released to soon and then it not being available so I put references in the UITableViewCell to hold the UIFont until the end of that Cell's life.
I have also searched around the internet and haven't found that much on this specifics.
Also here is an image of my stack trace from debugger:
http://i.stack.imgur.com/gWC5L.png
Any ideas?
Did I provide enough info?
Thanks

Answer 1

I think your question is answered here:
UIStringDrawing methods don't seem to be thread safe in iOS 6
The short version: sizeWithFont, and most other UIKit methods, are not thread safe when you're using it on the screen (rather than using it to pre-render).
The good news: look at Adam Swinden's answer in that thread; he explains how to get the same result in iOS6 with CoreText instead of UIKit.