1. An postfix M means the file has been modified since the last "commit" and an A means this is a file that has been added since then.
2. what is keeping these views from being deallocated?
Views are always part of a view hierachy and they will always have an owner wit ha strong reference: their superview
3. the didSelectRowAtIndexPath method will simply deselect the row with an animation, while willSelectRowAtIndexPath makes sure that you can only select rows with actual search results.
4. A nib, also called a xib, is very much like a storyboard except that it only contains the design for a single thing. That thing can be a view controller but it can also be an individual view or table view cell. A nib is really nothing more than a container for a "freeze dried" object that you can edit in Interface Builder
Xib or nib? a xib file is compiled into a nib file that is put into your application bundle. the term inb mostly stuck for historical reasons(it stands for NeXT Interface Builder).
原文：http://www.cnblogs.com/glee/p/4497028.html