Xcode doesn't show the line that causes a crash

Every time my app crashes Xcode highlights the UIApicationMain() call in the main() function as the line that caused the crash. In some cases that used to be normal (segmentation fault for example) but the crash I am trying to deal with is a simple SIGABRT with detailed information logged in the console:

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFDictionary setObject:forKey:]: attempt to insert nil value (key: Date)'

Xcode used to show the line just right with older SDKs but since i upgraded to Xocde 4.2 that changed. It is pretty obvious that Xcode knows exactly what caused the crash (or could know), but its still not showing the actual line. Is there any fix or workaround for this?

Solution 1:

You should also ensure that you have breakpoints set for all exceptions. This will cause Xcode to stop at the line where the exception is occurring. Do the following [in Xcode 4]:

1. In the Project Navigator on the left side of Xcode, click on the breakpoint navigator (almost all the way to the right hand side of the top button bar. The icon looks like a fat right arrow).

2. At the bottom of the navigator, click the "+" button.

3. Click "Add Exception Breakpoint".

4. A new breakpoint will be created. It should be configured as needed but you can tweak its behavior.

5. Run your project and reproduce the exception.

Also you mentioned that you linked to some 3rd party libraries/frameworks. If the exception is occurring within those frameworks then you are going to have a hard time since the code is compiled and Xcode can't actually show you the line that caused the exception. If this is the case and you are certain you are using the libraries correctly, then you should file a bug report to the maintainers of those libraries.

Solution 2:

Simply follow the instructions on this StackOverflow answer:

Enable Zombies

Basically, you just need to "Enable Zombies". Then Xcode should break at whichever line caused the problem.

(It is absolutely shocking that, even in 2017, Xcode still has this turned off by default. Why would you not want to see the line that caused the problem ? And "Enable Zombie Objects" ?! Really ?! Do the Xcode authors really believe that this is a useful name, which would make any kind of sense to new developers ? It is depressing how poor Xcode's rating is, year after year, in the App Store. No one is listening...)

Solution 3:

Edit the current scheme and enable NSZombieEnabled, MallocStackLogging, and guard malloc. Then, when your App crashes, type this in the gdb console:

(gdb) info malloc-history 0x543216

Replace 0x543216 with the address of the object that caused the NSInvalidArgumentException and it should give you a much more useful stack trace, showing the lines of your code that are causing the crash.