title: Adding UIButton To UITableView Programmatically Wrong Spot
body: <p>I'm trying to get a UIButton added to a TableView, where it sits in the bottom right corner of the table view, 20 from the right edge, and 20 from the bottom.  However, it ends up sticking the button at the top left edge.  What am I doing wrong?</p>
  
  <pre><code>UIButton *goToTop = [UIButton buttonWithType:UIButtonTypeCustom];
      [goToTop setImage:redGo forState:UIControlStateNormal];
      [goToTop addTarget:self action:@selector(beginCampaign) forControlEvents:UIControlEventTouchUpInside];
      [goToTop setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
      [goToTop.layer setBorderColor:[[UIColor redColor] CGColor]];
      [self.tableView addSubview:goToTop];
  
      goToTop.translatesAutoresizingMaskIntoConstraints = NO;
      /* Leading space to superview */
      NSLayoutConstraint *leftButtonXConstraint = [NSLayoutConstraint
                                                   constraintWithItem:goToTop attribute:NSLayoutAttributeRight
                                                   relatedBy:NSLayoutRelationEqual toItem:self.tableView attribute:
                                                   NSLayoutAttributeLeft multiplier:1.0 constant:20];
      /* Top space to superview Y*/
      NSLayoutConstraint *leftButtonYConstraint = [NSLayoutConstraint
                                                   constraintWithItem:goToTop attribute:NSLayoutAttributeBottom
                                                   relatedBy:NSLayoutRelationEqual toItem:self.tableView attribute:
                                                   NSLayoutAttributeTop multiplier:1.0f constant:20];
      /* Fixed width */
      NSLayoutConstraint *widthConstraint = [NSLayoutConstraint constraintWithItem:goToTop
                                                                         attribute:NSLayoutAttributeWidth
                                                                         relatedBy:NSLayoutRelationEqual
                                                                            toItem:nil
                                                                         attribute:NSLayoutAttributeNotAnAttribute
                                                                        multiplier:1.0
                                                                          constant:60];
      /* Fixed Height */
      NSLayoutConstraint *heightConstraint = [NSLayoutConstraint constraintWithItem:goToTop
                                                                          attribute:NSLayoutAttributeHeight
                                                                          relatedBy:NSLayoutRelationEqual
                                                                             toItem:nil
                                                                          attribute:NSLayoutAttributeNotAnAttribute
                                                                         multiplier:1.0
                                                                           constant:60];
      /* 4. Add the constraints to button's superview*/
      [self.tableView addConstraints:@[leftButtonXConstraint, leftButtonYConstraint, widthConstraint, heightConstraint]];
  </code></pre>
  
  <p>Here is how I would like it:</p>
  
  <p><a href="https://i.stack.imgur.com/8Pn6O.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/8Pn6O.png" alt="enter image description here"></a></p>
  
  <p>Here is how it appears:</p>
  
  <p><a href="https://i.stack.imgur.com/8H6iJ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/8H6iJ.png" alt="enter image description here"></a></p>