title: *** Assertion failure in -[UIView _addConstraint:],
body: <p>I am getting below error when I try to add constraint to view.</p>
  
  <p><code>*** Assertion failure in -[UIView _addConstraint:], /SourceCache/UIKit/UIKit-2903.23/NSLayoutConstraint_UIKitAdditions.m:518</code></p>
  
  <p><strong>code</strong></p>
  
  <pre><code>[self.tabBar removeConstraint:self.bottomSpace];
  [self.view removeConstraint:self.bottomSpace];
  self.bottomSpaceForTabBar.constant = ...;
  [self.view addConstraint:self.bottomSpace];
  </code></pre>
  
  <p><code>self.bottomSpace</code> is added in IB and I have IBOutlet it.</p>