App crashes only after second execution only in Release configuration

Question

Hey all,

i know this is probably not an easy question to answer, as it's hard to describe on my hand. I have an app that runs without problems on the device in Debug Configuration (also multiple times).

Once I put it into Release Configuration (which I need before publishing?), the app starts without problems and I can proceed to the next page, where I show an core-plot graph. BUT only if I run it from xcode. As soon as I end the App and start it again, it opens without problems, but on the next page, it crashes. Now I don't have anything to debug other than the crash report:

  Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0xcf10000a
Crashed Thread:  0

Thread 0 Crashed:
0   libobjc.A.dylib                 0x000026f2 objc_msgSend + 14
1   StandbyCheck                    0x0001fbea -[CPXYTheme newGraph] (CPXYTheme.m:36)
2   StandbyCheck                    0x00007c06 -[SCGraphCell initWithStyle:reuseIdentifier:] (SCGraphCell.m:28)
3   StandbyCheck                    0x00076b4a -[TTTableViewDataSource tableView:cellForRowAtIndexPath:] (TTTableViewDataSource.m:128)
4   UIKit                           0x0007797a -[UITableView(UITableViewInternal) _createPreparedCellForGlobalRow:withIndexPath:] + 514
5   UIKit                           0x000776b0 -[UITableView(UITableViewInternal) _createPreparedCellForGlobalRow:] + 28
6   UIKit                           0x00037e78 -[UITableView(_UITableViewPrivate) _updateVisibleCellsNow] + 940
7   UIKit                           0x000367d4 -[UITableView layoutSubviews] + 176
8   StandbyCheck                    0x000734b8 -[TTTableView layoutSubviews] (TTTableView.m:226)

[...]

Now, can someone point in any direction? What are the differences in Debug/Release Modes? How could I possibly debug this failure?

I've been searching for hours now, please help me :( Thanks, Dennis

Answer 1

As far as I can tell, there's nothing in that line of CPXYTheme.m that would cause a crash. Particularly as it's a call to self, with an argument that was constructed in the method where the crash occurs. OK, so that leaves the obvious possibility of a concurrency problem - particularly as the crash occurs only in some configurations and not all the time. What are you doing on other threads that might affect the lifetime of your CPXYTheme object, or the SCGraphCell, or any object that "owns" them (the table view data source, view controller and so on)?