What's the difference of UIView frame and bounds.

UIView and its subclasses all have the properties "frame" and "bounds". What's the difference?

The frame of an UIView is the rectangle, expressed as a location (x,y) and size (width,height) relative to the superview it is contained within.
The bounds of an UIView is the rectangle, expressed as a location (x,y) and size (width,height) relative to its own coordinate system (0,0).

Difference between delegate and data source?

 http://stackoverflow.com/questions/2232147/whats-the-difference-between-data-source-and-delegate