How to handle the Xcode warning “no previous prototype for function…”?

Question

This warning is popping up a bunch in some third party libraries.

Is there a way to handle it without modifying the code (e.g. ignore the warning)?

If I have to

Answer 1

In Xcode4, go to your project's Build Settings. Search for "prototype". There should be an option called "Missing Function Prototypes"; disable it. You can also do this to the specific target(s) in question.

Answer 2

There are no warnings if such a function is defined as inline.

This may suffice as long as your function is optimized for inline use. http://msdn.microsoft.com/en-us/library/1w2887zk.aspx

Answer 3

Usually with warnings like this you can just define a function prototype at the top of your file, for instance:

BOOL FBIsDeviceIPad();

But in C a method with nothing between the braces, i.e. () actually implies there are an arbitrary number of parameters. Instead the definition should become (void) to denote no parameters:

BOOL FBIsDeviceIPad(void);

...

BOOL FBIsDeviceIPad(void) {
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 30200
  if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad) {
   return YES;
  }
#endif
  return NO;
}