title: How do I add this constraint in Xcode? It seems my relatedBy: argument is wrong
body: <p>My code is below, as well as the image of my app. Basically I want to add a constraint in the <code>viewDidLoad</code> method for this view controller to align the two labels so they start at the same x position. For whatever reason, I'm getting this warning, though:</p>
  
  <blockquote>
    <p>Incompatible pointer to integer conversion sending 'UIView *' to parameter of type 'NSLayoutRelation' (aka 'enum NSLayoutRelation'); </p>
  </blockquote>
  
  <p>And when I run the app I get the following error:</p>
  
  <blockquote>
    <p><strong>* Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*</strong> +[NSLayoutConstraint constraintWithItem:attribute:relatedBy:toItem:attribute:multiplier:constant:]: Unknown layout attribute'</p>
  </blockquote>
  
  <p><img src="https://i.stack.imgur.com/jMW0k.png" alt="enter image description here"></p>
  
  <pre><code>NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:self.carMakeLabel attribute:NSLayoutRelationEqual relatedBy:self.view toItem:self.carModelLabel attribute:NSLayoutAttributeLeading multiplier:1.0 constant:0];
  
  [self.view addConstraint:constraint];
  </code></pre>