[FIXED] How to handle the Xcode warning "no previous prototype for function..."?

Issue

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 modify the code to fix it how do I do it?

Here's one of the code blocks that's causing a warning:

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

Solution

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;
}

Answered By - appmattus

Answer Checked By - Clifford M. (PHPFixing Volunteer)