Project Files
.xib
MainWindow_iPhone.xib and MainWindow_iPad.xib contain the interface for your application. Double click to open in the interface builder.
.plist
ApName-Info.plist is the info property list which contains a list of the key-value pairs. These values specify things like the icon to display on the home screen, if the app needs a persistant WiFi connection, default language etc.
.h
Header files. Variables, methods etc declared in these.
.m
The code
MyAppName_Prefix.pch
Pre compiled header file. This is the global header file that is added to all project files. Use to add any global imports etc.
.nib
A xib file is compiled into a nib file which is what is actually run.
Bundle
The directory containing the executable and any resources the executable uses which is the output of the building the application.
#import (#include) and @class
In Objective-C #import is the same as standard C #include except that the file is only ever included once.
If you don’t want to import the header file for a class but want the compiler to know the class exists use ‘@class’ instead (much faster when compiling large projects):
@class SomeClassName;