title: Check if there is an emoji contained in a string
body: <p>I am getting the text size of a string with this</p>
  
  <pre><code>textSize = [[tempDict valueForKeyPath:@"caption.text"] sizeWithFont:[UIFont systemFontOfSize:12] constrainedToSize:CGSizeMake(280, CGFLOAT_MAX) lineBreakMode: NSLineBreakByWordWrapping];
  </code></pre>
  
  <p>The only problem I have is that if the string only contains an emoji, my app crashes. Is there an easy way to check for emojis or do I have to create an array with all possible emojis and then check for them using that?</p>
  
  <p>error:</p>
  
  <pre><code>-[NSNull sizeWithFont:constrainedToSize:lineBreakMode:]: unrecognized selector sent to instance 0x3aa88a60
  
  
  if ([tempDict valueForKeyPath:@"caption.text"]){
              NSLog(@"%@", [tempDict valueForKeyPath:@"caption"]);
              //Measure the message label box height
              textSize = [[tempDict valueForKeyPath:@"caption.text"] sizeWithFont:[UIFont systemFontOfSize:12] constrainedToSize:CGSizeMake(280, CGFLOAT_MAX) lineBreakMode: NSLineBreakByWordWrapping];
              int height = 320 + 20 + textSize.height;
              [cellHeight addObject:[NSNumber numberWithInt:height]];
  }
  </code></pre>