gistfile1.txt

// A view that uses Lion's auto layout code to automatically "stack" views horizontally or vertically. It optionally resizes added subviews along the non-aligned axis.
// It resizes itself based on its content.

// ##############################################################

//
//  CStackView.h
//  SceneKitTest
//
//  Created by Jonathan Wight on 2/19/12.
//  Copyright (c) 2012 toxicsoftware.com. All rights reserved.
//

#import <Cocoa/Cocoa.h>

@interface CStackView : NSView

@property (readwrite, nonatomic, assign) BOOL constrainSubviewSize;
@property (readwrite, nonatomic, assign) NSLayoutConstraintOrientation orientation;

@end

// ##############################################################

//
//  CStackView.m
//  SceneKitTest
//
//  Created by Jonathan Wight on 2/19/12.
//  Copyright (c) 2012 toxicsoftware.com. All rights reserved.
//

#import "CStackView.h"

@interface CStackView ()
@property (readwrite, nonatomic, strong) NSLayoutConstraint *endConstraint;
@end

#pragma mark -

@implementation CStackView

- (id)initWithFrame:(NSRect)inFrame
    {
    if ((self = [super initWithFrame:inFrame]) != NULL)
        {
		self.translatesAutoresizingMaskIntoConstraints = NO;

        _constrainSubviewSize = YES;
		_orientation = NSLayoutConstraintOrientationHorizontal;
        }
    return(self);
    }

#if 1
- (void)drawRect:(NSRect)dirtyRect
	{
	[[NSColor grayColor] set];
	NSRectFill(self.bounds);
	}
#endif

- (void)addSubview:(NSView *)inView
	{
	[super addSubview:inView];
	
	const NSLayoutAttribute theFixedDimension = self.orientation == NSLayoutConstraintOrientationHorizontal ? NSLayoutAttributeWidth : NSLayoutAttributeHeight;
	const NSLayoutAttribute theDynamicDimention = self.orientation == NSLayoutConstraintOrientationHorizontal ? NSLayoutAttributeHeight : NSLayoutAttributeWidth;
	const NSLayoutAttribute theNearEdge = self.orientation == NSLayoutConstraintOrientationHorizontal ? NSLayoutAttributeLeft : NSLayoutAttributeTop;
	const NSLayoutAttribute theFarEdge = self.orientation == NSLayoutConstraintOrientationHorizontal ? NSLayoutAttributeRight : NSLayoutAttributeBottom;

	if (self.constrainSubviewSize == YES)
		{
		inView.translatesAutoresizingMaskIntoConstraints = NO;

		[self addConstraint:[NSLayoutConstraint constraintWithItem:inView attribute:theFixedDimension relatedBy:NSLayoutRelationEqual toItem:NULL attribute:NULL multiplier:0 constant:inView.frame.size.width]];
		[self addConstraint:[NSLayoutConstraint constraintWithItem:inView attribute:theDynamicDimention relatedBy:NSLayoutRelationEqual toItem:self attribute:theDynamicDimention multiplier:1 constant:0]];
		}
			
	if (self.subviews.count == 1)
		{
		[self addConstraint:[NSLayoutConstraint constraintWithItem:inView attribute:theNearEdge relatedBy:NSLayoutRelationEqual toItem:self attribute:theNearEdge multiplier:1.0 constant:0.0]];
		}
	else
		{
		NSView *thePenultimateView = [self.subviews objectAtIndex:self.subviews.count - 2];
		
		[self addConstraint:[NSLayoutConstraint constraintWithItem:inView attribute:theNearEdge relatedBy:NSLayoutRelationEqual toItem:thePenultimateView attribute:theFarEdge multiplier:1.0 constant:0.0]];
		}
		
	if (self.endConstraint != NULL)
		{
		[self removeConstraint:self.endConstraint];
		self.endConstraint = NULL;
		}
	self.endConstraint = [NSLayoutConstraint constraintWithItem:self attribute:theFarEdge relatedBy:NSLayoutRelationEqual toItem:inView attribute:theFarEdge multiplier:1.0 constant:0.0];
	[self addConstraint:self.endConstraint];
	}
	
- (void)willRemoveSubview:(NSView *)subview;
	{
	const NSLayoutAttribute theFarEdge = self.orientation == NSLayoutConstraintOrientationHorizontal ? NSLayoutAttributeRight : NSLayoutAttributeBottom;

	if (self.endConstraint != NULL)
		{
		[self removeConstraint:self.endConstraint];
		self.endConstraint = NULL;
		}

	if (self.subviews.count > 1)
		{
		NSView *thePenultimateView = [self.subviews objectAtIndex:self.subviews.count - 2];	

		self.endConstraint = [NSLayoutConstraint constraintWithItem:self attribute:theFarEdge relatedBy:NSLayoutRelationEqual toItem:thePenultimateView attribute:theFarEdge multiplier:1.0 constant:0.0];
		[self addConstraint:self.endConstraint];
		}
	}

@end