Crash in Release Mode while generating NSString with arguments

Question

I have written Log helper class which has couple of Log functions. All is working well in DEBUG mode. But when I run my code is release mode it is crashing. Below is the code snippet:

+ (void)info:(NSString *)format, ...
{
    va_list args;
    va_start(args, format);
    va_end(args);

    NSString *formatedMessage = [[NSString alloc] initWithFormat:[NSString stringWithFormat:@"INFO %@",format] arguments:args];
}

While creating formatedMessage app is getting crash with below excecption:

If I set

Build Setting->optimization level to NONE

in Release mode all works smooth. Any idea to fix with Optimization Level to

Fastest-Smallest

in Release mode

But why I am unable to understand why its used to work with older version of xcode < 8.3 — Bhumeshwer katre, Apr 13 '17 at 18:12
It's probably a memory optimization. It was plain luck that it used to work. It is analogous to using an object pointer after the object has been deallocated. Doing so just might work under just the right conditions. — rmaddy, Apr 13 '17 at 18:16

score 2 · Accepted Answer · answered Apr 13 '17 at 18:09

You seem to be calling va_end too soon. Try:

+ (void)info:(NSString *)format, ...
{
    va_list args;
    va_start(args, format);

    NSString *formatedMessage = [[NSString alloc] initWithFormat:[NSString stringWithFormat:@"INFO %@",format] arguments:args];

    va_end(args);
}

Crash in Release Mode while generating NSString with arguments

1 Answers1