New NSLayoutAnchor class

I was reading through iOS 9's API diffs, and found this gem: NSLayoutAnchor.

Instead of creating an NSLayoutConstraint objects directly, you start with one of the UIView, NSView, or UILayoutGuide objects you wish to constrain, and select one of that object’s anchor properties.

// Creating constraints using NSLayoutConstraint
[NSLayoutConstraint
 constraintWithItem:subview
 attribute:NSLayoutAttributeLeading
 relatedBy:NSLayoutRelationEqual
 toItem:self.view
 attribute:NSLayoutAttributeLeadingMargin
 multiplier:1.0
 constant:0.0].active = YES;
 
[NSLayoutConstraint
 constraintWithItem:subview
 attribute:NSLayoutAttributeTrailing
 relatedBy:NSLayoutRelationEqual
 toItem:self.view
 attribute:NSLayoutAttributeTrailingMargin
 multiplier:1.0
 constant:0.0].active = YES;
 
// Creating the same constraints using Layout Anchors
UILayoutGuide *margin = self.view.layoutMarginsGuide;
 
[subview.leadingAnchor constraintEqualToAnchor:margin.leadingAnchor].active = YES;
[subview.trailingAnchor constraintEqualToAnchor:margin.trailingAnchor].active = YES;

Amazing.