simlify layout work for iOS

I wrote this to separate UIView`s layout job to layout manager , so we can add a new layout easily

• 1.(UIView + Layout) category add five layout property to UIView ,so all UIView can participate the layout process

• 2.DHLayoutView is a layout view that used to layout its subviews, it overrides UIView`s layoutSubviews method to provide its own layout, I provide two subclass, DHHorizontalLayoutView and DHVerticalLayoutView for you to use.

• 3.DHLayoutManager is used to do the actual job for DHLayoutView, it has a subclass DHHoritalLayoutManager for DHHorizontalLayoutView ,and DHVerticalLayoutManager for DHVerticalLayoutView

+ DHLayoutView                          
    + DHHorizontalLayoutView            
    + DHVerticalLayoutView

+ DHLayoutManager
    + DHHorizontalLayoutManager
    + DHVerticalLayoutManager

• It was designed to be work with Xib (of course you can use it in Code) , you can set all the property in section, and you can learn more in the Demo.