title: How can I determine whether a TextField contains a numeric string?
body: <p>I get a value from a <code>TextField</code> and I need to check if there's a number in it. Whether it's a float or an integer doesn't really matter, but definitely a "Number"</p>
  
  <p>How can I catch this?</p>
  
  <p>This is what I'm doing so far - even if the obj is 123 (actually a number), the condition is false, so I can't get into the <code>if</code>. I already tried <code>NSValue</code> and <code>Data</code>, but with the same results.</p>
  
  <pre><code>id obj = self.textArea.text;
  
  if ([obj isKindOfClass:[NSNumber class]]) {
      self.weight = [NSNumber numberWithFloat:([self.textArea.text floatValue])];
  </code></pre>