only change background color for iOS

Make buttons work for iOS

Use preprocessor to only include iOS for form controller

Fix ListHeaderFooterController initializer

Merge pull request #23 from sereisoglu/master

CGSize extension added.

fix for ios9+

fix for ios9+

expose anchor method as open

use default 0 value for constants

Merge pull request #16 from michaelversus/patch-1

Add constraint Method with enum

update readme