add ARC support + example define BackView from Nib

[bsorrentino]

[alexzielenski]

"supporting ARC" seems like a lot of messy code added and it's not really required. You can disable ARC on a per-file basis using the compiler flag "-fno-objc-arc"

[bsorrentino]

In real, i would have had to reduce code, introducing arc ... But i preferred use preprocessor directive to keep your original code. I think is a good idea move to arc to stay on track

[christophercotton]

In looking at the changes, it might just be easier and cleaner to just move the code to ARC. Most people are using iOS 6.0, and soon iOS 7.0. And, it is easy with Cocoapods to just enable it for a single project if for some reason they haven't yet moved to ARC.

I feel as though having the preprocessor directives makes the code much harder to read.

[y0unghe]

How to define the backview to reveal. You reva cell's contentview as backview. But change it to uiview won't work.