Category on UIView to simplify the creation of common layout constraints. The code is described and introduced in this blog post.
The demo project is most of the way towards drawing a robot made of views arranged using all the category methods:
Here's the header to save you a click:
/// Return a frameless view that does not automatically use autoresizing (for use in autolayouts)
+(id)autoLayoutView;
/// Centers the receiver in the superview
-(NSArray *)centerInView:(UIView*)superview;
-(NSLayoutConstraint *)centerInContainerOnAxis:(NSLayoutAttribute)axis;
// Pin an attribute to the same attribute on another view. Both views must be in the same view hierarchy
-(NSLayoutConstraint *)pinAttribute:(NSLayoutAttribute)attribute toSameAttributeOfView:(UIView *)peerView;
/// Pins a view to a specific edge(s) of its superview, with a specified inset
-(NSArray*)pinToSuperviewEdges:(JRTViewPinEdges)edges inset:(CGFloat)inset;
/// Pins a view to specific edge(s) of its superview, with a specified inset, using the layout guides of the viewController parameter for top and bottom pinning if appropriate
-(NSArray*)pinToSuperviewEdges:(JRTViewPinEdges)edges inset:(CGFloat)inset usingLayoutGuidesFrom:(UIViewController*)viewController;
/// Pins a view to all edges of its superview, with specified edge insets
-(NSArray*)pinToSuperviewEdgesWithInset:(UIEdgeInsets)insets;
/// Pins a view's edge to a peer view's edge. Both views must be in the same view hierarchy. Deprecated as of iOS7 to allow for layout guides instead.
-(NSLayoutConstraint *)pinEdge:(NSLayoutAttribute)edge toEdge:(NSLayoutAttribute)toEdge ofView:(UIView*)peerView __deprecated;
/// Pins a view's edge to a peer view's edge, with an inset. Both views must be in the same view hierarchy. Deprecated as of iOS7 to allow for layout guides instead.
-(NSLayoutConstraint *)pinEdge:(NSLayoutAttribute)edge toEdge:(NSLayoutAttribute)toEdge ofView:(UIView *)peerView inset:(CGFloat)inset __deprecated;
/// Pins a view's edge to a peer item's edge. The item may be the layout guide of a view controller
-(NSLayoutConstraint *)pinEdge:(NSLayoutAttribute)edge toEdge:(NSLayoutAttribute)toEdge ofItem:(id)peerItem;
/// Pins a view's edge to a peer item's edge, with an inset. The item may be the layout guide of a view controller
-(NSLayoutConstraint *)pinEdge:(NSLayoutAttribute)edge toEdge:(NSLayoutAttribute)toEdge ofItem:(id)peerItem inset:(CGFloat)inset;
/// Pins a views edge(s) to another views edge(s). Both views must be in the same view hierarchy.
-(NSArray *)pinEdges:(JRTViewPinEdges)edges toSameEdgesOfView:(UIView *)peerView;
-(NSArray *)pinEdges:(JRTViewPinEdges)edges toSameEdgesOfView:(UIView *)peerView inset:(CGFloat)inset;
/// Set to a specific size. 0 in any axis results in no constraint being applied.
-(NSArray *)constrainToSize:(CGSize)size;
/// Set to a specific width or height.
-(NSLayoutConstraint *)constrainToWidth:(CGFloat)width;
-(NSLayoutConstraint *)constrainToHeight:(CGFloat)height;
// Set minimum and maximum sizes. 0 in any axis results in no constraint in that direction. (e.g. 0 maximumHeight means no max height)
-(NSArray *)constrainToMinimumSize:(CGSize)minimum maximumSize:(CGSize)maximum;
// Set a minimum size. 0 in any axis results in no constraint being applied.
-(NSArray *)constrainToMinimumSize:(CGSize)minimum;
// Set a maximum size. 0 in any axis results in no constraint being applied.
-(NSArray *)constrainToMaximumSize:(CGSize)maximum;
/// Pins a point to a specific point in the superview's frame. Use NSLayoutAttributeNotAnAttribute to only pin in one dimension
-(NSArray*)pinPointAtX:(NSLayoutAttribute)x Y:(NSLayoutAttribute)y toPoint:(CGPoint)point;
/// Spaces the views evenly along the selected axis. Will force the views to the same size to make them fit
-(void)spaceViews:(NSArray*)views onAxis:(UILayoutConstraintAxis)axis withSpacing:(CGFloat)spacing alignmentOptions:(NSLayoutFormatOptions)options;See the AutoLayoutDemo project for example usage.