Snippet for constraints in Visual Format Language, that center view vertically and horizontally in its superview.

CenterInContainerWithVFL.m

//  Vertical center in container
[superview addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:[superview]-(<=1)-[view]"
                                                                  options:NSLayoutFormatAlignAllCenterY
                                                                  metrics:nil
                                                                    views:viewDict]];
                                                                        
//  Horizontal center in container
[superview addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[superview]-(<=1)-[view]"
                                                                  options:NSLayoutFormatAlignAllCenterX
                                                                  metrics:nil
                                                                    views:viewDict]];