title: sizeWithAttributes causes crash on ios 6. Works in ios 7
body: <p>Since the sizeWithFont method is now deprecated I wanted to try the sizeWithAttributes which works as expected when running ios 7. But when I run it on ios 6 it causes a crash, and I can see that by looking at the header which looks like this.</p>
  
  <pre><code>- (CGSize)sizeWithAttributes:(NSDictionary *)attrs NS_AVAILABLE_IOS(7_0);
  </code></pre>
  
  <p>Since the sizeWithAttributes came from another category which is removed now I can't use it in ios 6 and under. </p>
  
  <p>What can I do about it? I can use sizeWithFont: if target is &lt; ios 7, but there must be a reason that it has been deprecated, thus I want to avoid it. </p>
  
  <p>Any ideas?</p>