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Stacks - Using stack views (requires iOS 9)

Version 1.3   05 Oct  2015   Add static quick actions
Version 1.2   27 Sep  2015   Hide a view for compact height
Version 1.1   06 July 2015   Adapting axis to view size classes
Version 1.0   22 June 2015   Initial version.
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Example of how to use UIStackView to simplify layout of horizontal and
vertical arrangements of views. See the following post for details:

http://useyourloaf.com/blog/easier-autolayout-with-stackviews.html

Also see this post for details on how to have the stack view automatically
adapt to size class changes:

http://useyourloaf.com/blog/adapting-stack-views-with-size-classes.html

The third view controller - HiddenViewController is an example of how to
use size classes to hide a view contained in a stack view. See this post
for details:

http://useyourloaf.com/blog/using-size-classes-to-hide-stack-view-contents.html

Quick actions allow the user to launch the app directly to one of the three tabs.
See this post for details:

http://useyourloaf.com/blog/adding-3d-touch-quick-actions.html