title: Using __IPHONE_7_0 and respondsToSelector
body: <p>I came across this code and I was wondering if the #ifdef check is redundant.</p>
  
  <pre><code>UIButton *doneButton = [[UIButton alloc] init];
  ...
  
  #ifdef __IPHONE_7_0
      if([self respondsToSelector:@selector(setEdgesForExtendedLayout:)])
          [doneButton setContentEdgeInsets:UIEdgeInsetsMake(0, 12, 0, -12)];
  #endif
  </code></pre>
  
  <p>I tried removing it and running it in iOS 6 and it ran fine. Is there some special case I need to be aware of in iOS 6/7 that causes it to not trigger or causes crashes?</p>