title: va_list crash on 64-bits simulator
body: <p>When using 64bits iOS simulator the init function below crashes with EXC_BAD_ACCESS (code=1) error. Would anyone know why ? And how to fix it properly.</p>
  
  <p>For information: 'format' is not nil, and it works just fine on 32bits simulator and any 32/64 bits iPhone/iPad devices.</p>
  
  <pre><code>void Log (NSString * format, ...)
  {
     va_list argList;
     va_start(argList, format);
     NSLogv(format, argList);
     NSString* string = [[NSString alloc] initWithFormat: format arguments: argList];
     va_end(argList);
  
  ...
  }
  </code></pre>
  
  <p>called first thing in AppDelegate</p>
  
  <pre><code>- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
  {
     Log(@"app options %@", launchOptions);
     ...
  }
  </code></pre>