title: Objective-C/iOS - Test for existence of C function?
body: <p>Is there a way to test for the existence of C functions in Objective-C? I'm looking for something like "respondsToSelector," but for C functions. </p>
  
  <p>More specifically, I'm trying to test for the existence of "UIGraphicsBeginImageContextWithOptions(CGSize size, BOOL opaque>, CGFloat scale)" in iOS.</p>
  
  <p>Thanks.</p>