title: NSPredicate with regex to check alphanumeric
body: <p>I want to check string with regex in Objective c. My code </p>
  
  <pre><code>NSString *regexAmazonOrder =@"[a-zA-Z0-9]*";
  NSPredicate *predicateAmazonOrder = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",regexAmazonOrder];
  
  if([predicateAmazonOrder evaluateWithObject:cardNumber.text])
  {
      NSLog(@"Its coming inside AMAZON ORDER EVALUATIONS");
      ...
  }
  </code></pre>
  
  <p>But its not working. Help me out. I know its simple but eating my mind!!! Thanks</p>